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^TURAL RESOURCES
UBKAKV
I.e. STATE UNIVERSITY D.H. HILL LIBRARY
S00218871 R
THIS BOOK IS DUE ON THE DATE
INDICATED BELOW AND IS SUB-
JECT TO AN OVERDUE FINE AS
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1992
JUL 0 3 200b
5M/7-87-871457
U. S. DEPARTMENT OF AGRICULTURE.
DIVISION OF BOTANY.
CONTRIBUTIONS
THE U. S. NATIONAL HERBARIUM.
Vol. V, No. 5.
ISSTJED ^TJ&XJST 1, 1900.
THE PLANT COVERING OF OCRACOKE ISLAND; A STUDY
IN THE ECOLOGY OF THE NORTH CARO-
LINA STRAND VEGETATION.
THOMAS H. KEARNEY. JR.
OK 178
K4
WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1900.
m]t ^, ;i. ^tll %xhnxvn
QKI78
K4
U. S. DEPARTMENT OF AGRICULTURE.
DIVISION OF BOTANY.
CONTRIBUTIONS
THE U. S. NATIONAL HERBARIUM.
Vol. V, No. 5.
iswtjp:i:> ^vuc^us'r i, looo.
THE PLANT COVERING OF OCRACOKE ISLAND; A STUDY
IN THE ECOLOGY OF THE NORTH CARO-
LINA STRAND VEGETATION.
THOMAS PI. KEAKNKY. JR.
WASHINGTON:
GOVERNMENT PRINTING OFFICE.
190 0.
LETTER OF TRANSMITTAL
U. S. Department of Agriculture,
Division of Botany,
Washington, D. C, Fehruary 38, 1900.
Sir: I have the honor to transmit herewith, for i^ublication as
Volume Y, No. 5, Contributions from the United States National Her-
barium, a manuscript b}^ Mr. T. H. Kearney, jr., assistant botanist,
entitled The Plant Covering of Ocracoke Island.
ResiDectfully,
Frederick V. Coville,
Botanist.
Hon. James Wilson,
Secretary of AgricuUiire.
II
CONTENTS.
Page.
Introduction 261
Climate 262
Temperature - 262
Sunshine - - 264
Atmospheric humidity.... 264
Precipitation _ 265
Wind - 266
Physiography 266
Geology and soils. 267
The plant formations, their composition and physiognoijiy 260
Sand-strand vegetation 270
Treeless, open formations 270
Beach formation 270
Dune formation 270
Evergreen tree and shrub formations 271
Tree formation : 271
Thicket formation 272
Salt-marsh vegetation _ _ , 272
Creek- marsh formation 272
Spartiua stricia association 272
Jiincus roemerianus association 273
Dune-marsh formation 274
Tidal flat formation 274
Pasture and ruderal plants _. 275
Cultivated plants 275
Ecological forms and adaptations to environment . . 275
Adaptations to the mechanical action of the wind and the instability of
the soil ^ 276
Adaptations for protecting the supply of water 277
Anatomy . 280
Species of the sand strand 285
Panicum amarutn 285
Mnhlenbergia filipes 285
Spartina patens 288
Spartina stricta. . 289
Chloris petraea 290
Uniola paniculata 292
Yucca aloif olia 298
Yucca gloriosa. '. 293
Myrica carolinensis 294
Myrica cerif era 294
Quercus virgini ana ... 294
Zanthoxylnni clava-herculis 295
Croton maritimus _ - 296
III
:V CONTENTS.
Anatomy — Continued. Page.
Species of the sand strand — Continued.
Ilex vomitoria ..- 296
Oenothera humifusa 297
Teucrium nashii 297
Physalis viscosa 298
Salt-marsh species . - 301
Triglochin striata 301
Spartina stricta 301
Juncus roemerianus .-. T^^
Sesuvium maritimum i/
Tissa marina r02
Kosteletzkya virginica 303
Ammania koehnei ?03
Vincetoxicum palustre. c - j
Lippia nodiflora c04
Monniera monniera ^)5
Solidago sempervirens £05
Aster tenuif olius 306
Aster subulatus ._ 306
Baccharis halimifolia 307
Iva frutescens 508
Borrichia frutescens 309
Geographical affinities of the flora - 312
List of plants collected and observed. 314
Bibliography 319
ILLUSTRATIONS.
Fig. 33. JIuhlenbergia filipes — transverse section of leaf 286
34. Muhlenhergia filipes — ventral epidermis of leaf 286
35. Mulilenhergia filipes — dorsal part of leaf blade ^ 286
36. Muhlenhergia filipes— xtortion of mestome bundle 287
37. Chloris p>etraea — leaf blade. . . . 290
38. Chloris petraea — ventral portion of leaf blade 291
39. Chloris petraea — large mestome bundle from leaf blade. 291
40. Chloris petraea— thx^e small mestome bundles from the blade 292
41 . Yucca aloifolia — leaf surface 293
42. Yucca aloifolia — a stoma - 293
43. Quercus virgi^iiau a— stellate hair from dorsal leaf surface 295
44. Croton maritimus — hair from dorsal leaf surface 296
45. Physalis v/scosjf— branched hair from leaf , 298
46. Tissa ??iari?ia— glandular hair from leaf margin 302
47. Lippia nodi/fora— stomata and hairs . „ 304
48. Iva frutescens — hair from ventral leaf surface 308
49. Borrichia frutescens — leaf section 309
50. Borrichia frutescens — leaf hairs 309
THE PLANT COVERIXG OF OCRACOKE ISLAND: A STUDY
IN THE ECOLOGY OF THE NORTH CAROLINA STRAND
VEGETATION.
By Thomas H. Kearney, Jr.
INTRODUCTION.
In October, 1898, in the course of field work for the United States
Department of Agriculture, the writer spent five days upon Ocracoke
Ishmd, North Carolina. Owing to its limited size, it was possible,
even in that short time, to explore somewhat thoroughly a considei*-
able part of the island. It is to be regretted that visits were not
made to the localit}^ earlier in the season, so that the plienologieal
develoj)ment of the vegetation could be studied. However, as most
of the characteristic plants of our southern Atlantic strand are rather
late in maturing, it is probable that a better season for a single visit
could not have been chosen. It was of course impossil)le to make
any valuable observations upon fecundation and dissemination,
important as these subjects are to the study of the geographical dis-
tribution of plants. AVliat is said here of Ocracoke will doubtless
apply, in a general Avay, to the other sandy reefs of the Xoi-tli Caro-
lina coast.
The object of this paper is a study of the ecology and geography of
the vegetation of the island, the several divisions of the suliject ))eiiig
presented in the following order:
(1) Climate; (2) physiography; (3) geology and soils; (4) the plant
formations, their composition and physiognomy; (5) ecological foinis —
adaptations to environment; (G) anatomy; (7) phytogeograplnCal
affinities of the flora.
The nomenclature used is mainly that followed in Hrittoii and
Brown's Illustrated Flora of the Northern United States and Canada,
but, in order that those who are interested in ecological work and are
not familiar with this nomenclature maj'find no difficulty in recognizing
the species described, the names used in the later works of Gray and of
Chapman are quoted in parentheses. A full list of all plants collected
or observed upon the island is appended, and here, again, familiar syno-
nj^ms are cited in parentheses. A list of the works quoted, Avith their
full titles, is given at the end of the paper.
In the i^reparation of the anatomical portion of the pap<'r, Mr.
261
-t!'J THE PLANT COVERING OF OCRACOKE ISLAND.
1 heodor Holm has rendered valuable assistance, and lie has kindly
furnished the drawings for figures Nos. 1 to 8, 17, and IS. The other
figures were drawn from nature hy the author.
CLIMATE.
The following data have been obligingly furnished ])y the United
States Weather Bureau. The observations were made at the Hatteras
Station, only a few miles northeast of Oeracoke.
TEMPERATURE.
Readings were taken in the shade.' The observations at Hatteras
cover a period of about twenty years. The average number of days
per annum with a temperature exceeding 6° C. (43° F.) is 365, Avhile at
Norfolk, Ya., the number is only 295. The sum total of temperatures
above 6° C. during the year averages 3,740.4:° C. (0,740° F.), which
is notably higher than the Norfolk figure of 3,359.4° C. (6,047.0° F.).
The normal mean temperature during the six consecutive hottest weeks
of summer is 25.0° C. (78.6° F.), as compared with the slightly higher
mean of 26.3° C. (79.3° F.) at Norfolk.
The normal annual temperature is 16.3° C. (61.4 F.), as comimred
with 14.8° C. (58.7° F.) at Cape Henry, Virginia, 15.0° C. (59.0° F.) at
Norfolk, Va., and 17.2° C. (63.0° F.) at Wilmington, N. C.
The normal monthly temperatures are as follows:
January .
February
March
April
May
June
Degrees C.
Degrees F.
7.6
1
45.7 1
8.1
46.6
10.0
50.1 1
u.o
57.2 ,
19.1
66.4 ;
3:13
74.0 '
.1
Degrees C. , Degrees P.
July
August . ..
September
October . .
November
December
25. 5
77.9
2.5. 2
77.4
2:3.2
7u. 7
18.0
64.5
13.1
55.6
9.0
48.2
The normal daily range of temperature for the whole year amounts
to 6.3° C. (11.3° F.),as compared with 8.2° C. (14.7° F.) atCapellenry,
8.8° C. (15.8° F.) at Norfolk, and 9.6° C. (17.3° F.) at Wilmington.
The normal dail}^ ranges for each month are as follows :
January .
February
March
April
May
June
Degrees C.
Degrees F.jj
7.0
12.7
7.1
12.8
7.2
12.9
6.9
12.5
6.4
^
11.5
5.7 1
1
10.3
Degrees C. Degrees F.
July
August
September
October . . .
November
December .
5.1
5. 3
10.0
9.3
9.6
10.2
11.3
12.8
' Consequently they do not represent the temperature to which most of the vege-
tation is actually exposed, being subject to insolation during the hours of sun-
shine. They are chiefly valuable for purposes of comparison with other climates.
TEMPERATURE CONDITIONS.
263
The absolute maximum temperature observed was 38. 8° C. (102° F )
as compared with 39.4° C. (103° F.) at Cape Henry, 38.8° C. (102° F )
at Norfolk, and 39.4° C. (103° F.) at Wilmington.
The absolute minimum temperature observed w as 13. 3° C. (8. 0° F )
ascomparedwith — 15.0° C. (5.0° F.) at Cape Henry, — 1G.G° C (2 0^
F.) at Norfolk, and — 12.8° C. (9.0° F.) at AVilmington.
The absolute monthly maxima and minima are as follows:
Month.
Maxi
mum.
Minimum.
Degrees C.
Degrees F.
Degrees C.
Degrees F.
Jamxary
26.1
22.8
29.4
30.0
33.9
38.8
37.2
36.1
a5.o
32.2
26.1
22.8
79
73
85
86
93
102
99
97
95
90
79
73
-10.0
-11.7
- 3.3
- 0.6
6.1
12. 8
16.1
16.6
10.0
5.5
-13.3
February.
U
March...
11
April..
26
May...
31
June
43
July
55
August
61
September _
62
October
50
November
43
December
28
8
The average date of the latest killing frost in spring is February
25, as compared with March 19 at Cape Henry, March 2G at Norfolk,
and March 15 at Wilmington. The latest recorded was April 5, as
compared with April 19 at Cape Henry, April 26 at Norfolk, and April
20 at Wilmington.
The average date of earliest killing frost in autumn is December 13,
as compared with November 14 at Norfolk and Cape Henry and
November 12 at Wilmington. The earliest killing frost recorded was
on November 12, as compared with November 14 at Cape Henry, Octo-
ber 15 at Norfolk, and October 13 at Wilmington.
From the above data the temperature may be characterized as fol-
lows: Warm, but not excessive, with a considerable sum total of
effective temperatures during the growing season, and usually mild
temperatures during the very brief dormant period. The normal
temperature is at least (j.5° C. above freezing point during every
month of the year. The normal amount of daily variation of tem-
perature is, according to the season, from 5° to 7° C, a relatively
very small range. The period between the average dates of the
earliest killing frost in autumn and of the latest in spring, which may
be taken as very roughly coinciding Avith the dormant period of most
of the vegetation, covers only seventy-four days.
264 THE PLANT COVERING OF OCRACOKE ISLAND.
SUNSHINE.
The observations cover a period of nearly thirty years. Normal
annual sunshine,^ stated in percentages of possible sunshine, 54, as
compared with 52 at Cape Henry, 51 at Norfolk, and 52 at Wilming-
ton. The monthly percentages are as follows:
Month.
January
February
March ..
April
Per
cent.
Month.
May —
June . . ,
July...
August
Per
cent.
Month.
Per
cent.
September
October...
November
December
Normal annual sunshine, stated in Irours, 2,392.2, as compared with
2,314.G at Cape Henry, 2,270.1 at Norfolk, and 2,312.7 at Wilmington.
The normal monthly number of hours of sunshine are:
Month.
Hours.
Month.
Hours. Month.
Hours.
144.7
143.7
193.4
216.0
Mav
256.2 September
208.3
February
March
AT»ril
238.9 October...
203.0
July
243.1 November
167.4
August -
216.9 j December
160.6
1
These records yield the result that the normal annual percentage
of sunshine is low compared with that in much of the territory of the
United States, especially west of the Mississippi River; but it is not
much less than that prevailing in other parts of the Southeastern
States, while it exceeds the percentages given for the northern portion
of the Atlantic slope.
ATMOSPHERIC HUMIDITY.
This is stated in percentages of possible saturation, which of course
varies at different seasons with the temperature, etc. Annual (for a
period of seven years), 81.4 as compared with 74 at Cape Henry, and 73
(during nine years) at Norfolk and Wilmington. Monthly, as follows :
Month.
Per
cent.
January .
February
March —
April
Month.
Per
cent.
Month.
May —
June ...
July....
August
September.
October
November.
December .
Per
cent.
The annual percentage thus shown is greater than that recorded
for any other station in the United States, excepting those in the
' These figures only approximate the real values. They are derived from statis-
tics of cloudiness.
RAINFALL.
265
Puget Sound region, and even there the excess over the Hatteras
figure is not great. Moreover, this humiditj^ is distributed throughout
the months of the year with remarkable uniformity, the variation
between any two months amounting to not more than o per cent.
PRECIPITATION.
This is stated in centimeters and inclies. Annual, 159.4 centimeters
{66.41 inches), as compared with 125.6 centimeters (52.34 inches) at
Cape Henrj^, 125.0 centimeters (52.1 inches) at Norfolk, and 130.4
centimeters (54.34 inches) at Wilmington. Monthlj^, as follows:
Month.
January.
February
March . . .
April
Cen-
time-
ters.
14.3
10.7
14.6
11.3
Inch
es.
5.91
4.47
6.10
4.73
Month.
May ...
June...
July...
August
Cen-
time-
ters.
11.0
10.9
15.4
15.3
Inch-
es.
4.60
4.57
6.43
6.a5
Month.
September
October . . .
November
December .
Cen-
time-
ters.
Inch-
15. 4
14.8
13.4
13.1
ti.44
6.17
5.18
5.47
The average annual number of rainy days is 123.8, as compared
with 125 at Cape Henry, 131.3 at Norfolk, and 128.8 at Wilmington.
The average monthl}^ number of raiu}^ days is as follows :
Month.
Days.
Month.
Days.
1
Month. Days.
January ,
15.9
10.3
11.9
8.4
May
June
10.0
9.6
10.3
10.3
September 13.7
February
October 7.5
July
November 6.7
April
August
December 9.5
At Hatteras the precipitation consists almost entirely of rain. Rain-
bearing storms usually approach from a westerl}' direction. AVinter and
spring rains are usuallj^ of light intensity and long duration, while
those of the summer and fall are more often brief and torrential in
character.
The results viewed comparatively are as follows: Tlie normal
annual rainfall is remarkably heavy, exceeding that at the nearest
station, Wilmington, by 30 centimeters. Only on the coast of Wash-
ington and Oregon does the total rainfall within tlie limits of tlie
United States notably exceed that of Hatteras. The normal varia-
tion between the month of least and that of greatest rainfall does
not exceed 5 centimeters, so that in ordinary seasons periods of
drought do not occur. The heaviest rainfall occurs in tlie months from
July to October. The average number of rainy days is large, about
one-third of the days of the year, and is distributed with relatively
great uniformity, varying from 6.7 days in the montli of least to 15.9
in the month of greatest number of rainy days.
Of dewfall no statistics could be obtained.
266
THE PLANT COVERING OF OCRACOKE ISLAND.
WIND.
The average annual maximum velocity of the wind is 21.4 kilome-
ters (13.3 miles) per hour, as compared with 23.2 kilometers at Cape
Henry, 15.1 at Norfolk, and 15.4 at Wilmington. The average monthly
maximum velocities, stated in kilometers and miles, are as follows:
Month.
January.
February
March . . .
April
Kilo-
me-
ters.
Miles
25.0
15.5
24.5
15.2
25.2
15.6
24.2
15.0
Month.
May ...
June . . .
July...
August
Kilo-
me-
ters.
Miles
20.3
12.6
21.3
13.2
18.5
11.5
19.7
12.2
Month.
September
October . . .
November
December.
Kilo-
me-
ters.
17.2
18.4
19.8
24.0
Miles
10.7
11.4
12.3
14.9
In regard to direction, the winds of midwinter are usually from the
north, while those of midsummer are usually from a little west of
south.
As thus shown, the average velocity of the wind is considerable, and
the amount of its variation from month to month is remarkably" slight.
The highest average of course prevails in winter and early spring. In
midwinter, when the winds are normally strongest and therefore most
affect the perennial, especially the woody vegetation, their prevailing
direction is almost due south (from the north), hence, in the case of
Ocracoke, from tlie mainland.
In regard to temperature, rainfall, and atmospheric humidity the
climate of Ocracoke and Hatteras is suitable for a vigorous forest
growth. But the exposure to strong winds, and the peculiar soil con-
ditions, neutralize these favorable factors and give it a typical strand
vegetation, which much resembles that of deserts. In the neighbor-
hood of Norfolk and of Wilmington, where conditions of temxjerature
and of humidity are really somewhat less suitable than at Hatteras to
the most luxuriant develo]3ment of j^lants, the virgin growth is almost
eveiywhere dense forest, because there the inimical conditions are
absent.
PHYSIOGRAPHY.
Ocracoke Island is part of that long chain of narrow sand reefs
which fringes the southern Atlantic Coast of the United States, and
which forms the eastern bariier to a series of almost land-locked bays
and sounds. Ocracoke lies in longitude 76° west and latitude 35° 10'
north, and is therefore somewhat south of the center of the North
Carolina coast. It is separated from Hatteras Reef by the 0.8 kilo-
meter (one-half mile) wide strait known as Hatteras Inlet, and from
Portsmouth, the next island below, by Ocracoke Inlet, 3 kilometers
(nearly 2 miles) wide. Ocracoke itself is about 26 kilometers (16
miles) in length, and extends from that great bulge of the coast line
GEOLOGY OF THE ISLAND. 267
known as Cape Ilatteras, in a southwesterly direction. Tlio islancrs
greatest width near its lower end falls short of 3 kilometers; the aver-
age width is only 1 kilometer, while in places it is even narrower.
Outside rolls the Atlantic, while between island and mainland stretch
the waters of Pamlico Sound, here from 30 to 45 kilometers (18 to 27
miles) wide. Pamlico differs from the shallower Albemarle Sound 1o
the north in the important respect that its water is always salt, while
Albemarle is normally fresh.
Near the so tith western extremity of the island a broad expanse of
tidal flat separates the higher land of the village of Ocracoke from
the Atlantic beach. One and one-half kilometers or so toward the
northeast this lagoon disappears, and dry land extends from the flat
sandy beach and the salt marshes which border the Sound to the
dunes which front the ocean. Into these marshes penetrate tiny
ci'eeks, whose ramifications cut the lower part of the island in all
directions. Almost the whole area is divided between sand strand
and tidal mai'sh. Much of it is only 1 meter or less above normal
high tide and subject to overflow when strong easterly gales a re blow-
ing, or when stiff breezes from the opposite quarter mass the waters
of Pamlico Sound against the western shore of the island. The high-
est land on Ocracoke is rex^resented by sand dunes often 3, sometimes
8 meters high. These are usually regular in form and fairly well
fixed by the vegetation. Those that abut upon the outer beacli or
rise amid the mud flats are particularly regular and dome-shaped.
GEOLOGY AND SOILS.
Of the geology of Ocracoke and its neighbor Ilatteras, we have
comparatively little knowledge. Shaler^ has jidvanced the theory
that these reefs were built up from the detritus which resulted from
the glacial excavation of Delaware and Chesapeake bays. Kerr-
describes Ilatteras as a "sort of delta." "The action," he says, "of
the tides and ocean ctirrents, the Gulf stream and Arctic current
meeting at this i^oint, accumulates upon Ilatteras tlie river silt wliieh
reaches the sea by way of the Chesapeake as well as that of tin' rivers
which discharge their burdens through the inlets about this point ami
southward. * * * Ilatteras is not a modern phenomenon. It is
at least as old as the Cretaceous; tlie Quaternary as well as tlie Ter-
tiary of this coast region of North Carolina are laid down ui)on an
eroded surface of Cretaceous rock." From measnrements elsewhere
made, the probable depth beneath the surface of the Cretaceons for-
mation on Ilatteras and (Ocracoke would be somewliere between I'on
and 300 meters. lam not aware that borings of any <'onsiderabhMleptJi
1 Proc. Bost. Soc. Nat. Hist., vol. 14, pp. 110 to 121. 1872.
•^Bul. Wash. Phil, boc, vol. (5, pp. '-38 to :JU. 1884.
268 THE PLANT COVERING OF OCRACOKE ISLAND.
have been made upon these islands.^ Kerr further states that * ' the reef
is increasing in continuity and breadth." But this is not the gen-
eral opinion, for it is said that there is to-daj' water of considerable
depth where houses stood upon Ocracoke within the memory of living
men, and it is stated^ that "a fine fig orchard and many peach trees,
with a fine potato patch and garden," occupied earlier what is now
Hatteras Inlet. That the present tendency of this whole coast line is
one of subsidence can hardly be disputed.
Beneath the superficial Recent deposits of dune sands and salt-
marsh silt which cover the greater part of the island lie the sands
and clays of the Columbia formation, which extend to a considerable
but unascertained depth. This and the Recent accumulations are
the onh^ geological formations of this part of the coastal plain which
need be considered in relation to the existing plant covering.
Excepting the areas occupied by creeks and salt marsh, the soil of
Ocracoke is a fine white marine sand, almost everywhere devoid of
any considerable admixture of humus. Only in the live-oak groves
is there enough A^egetable matter present to give the sand a gray
color. There is doubtless some quantity of calcium carbonate in the
soil, owing to the presence of small particles of shells washed up by
the waves and scattered b}^ the wind.-^
As much of the island is subject to occasional inundation and to
the deposition of spray by the winds, the soil content of sodium chlo-
rid must be considerably greater at times than in ordinary inland soils.^
There is no lack of moisture in this sandy substratum. Even in the
driest looking beach sand, water usually stands at a depth of only 15
to 30 centimeters (6 to 12 inches) from the surface. The superficial
layer of the sand acquires a great amount of heat on sunny days and
becomes thoroughly desiccated, in which condition it is subject to
being blown about by the wind, its degree of coherenc}^ depending
upon the character of the vegetation. At night, however, sand gives
up its heat rapidly and absorbs much dew, if conditions are favorable.'^
The soil of the salt marsh, which appears to be usually a thin sheet
' The succession of strata in the North Carolina coastal plain, where exposed
in the valleys of the Neuse and Cape Fear rivers, is given as follows, beginning
with the oldest:
(1) Potomac gravel, sands, and clays.
(2) Cretaceous sands and clays.
(3) Tertiary (Eocene and Miocene) marls and clays.
(4) Lafayette (yellowish and brownish sands and loams).
(5) Columbia sands, gravels, and clays.
2W. L. Welch, Bui. Essex Inst., vol. 17, pp. 87 to 42. 1886.
■^According to Contejean (Geogr. Bot.),the proportion of calcium carbonate
thus supplied to the strand soils is insignificant except near the wave limit, the
particles being soon dissolved by the carbon dioxide contained in rain water and
then washed down through the readily permeable soil.
^Sea water contains from 2.7 to 3.2 per cent of NaCl.
^Warming, Lehrbuch, p. 66.
ECOLOGICAL CROUPS. 269
of fine, brown silt overlying a stiff, bluish ehiy, contains orj^^anic mat-
ter in considerable quantity and is therefore capable of supporting a
denser plant growth than is found upon the sands. It is of course
saturated with salt or brackish water.
There is no outcrop of any kind of rock on tlic island.
THE PLANT FORMATIONS, THEIR COMPOSITION AND PHYSIOG-
NOMY.
The various assemblages of species and individuals which make up
the plant covering of Ocracoke Island may be classified as follows:*
L Sand-strand vegetation.
1. Treeless (open).
(a) Beach formation: Croton-Physalis association.
(b) Dune formation: * Uniola-Yucca association.
3. Evergreen trees and shrubs.
(a) Tree formation: Quercus virginiana association.
(6) Thicket formation: Ilex vomitoria association.
II. Salt-marsh vegetation.
1. Creek-marsh (closed) formation.
(a) Spartina stricta association.
(b) Juncus roemerianus association.
3. Dune-marsh formation; Lippia-Monniera association.
3. Tidal flat (open) formation: Sesuvium-Tissa association.
III. Pastures and ruderal plants.
IV. Cultivated plants.
It is not to be supposed that the severial groups are always or even
commonly sharply defined. On the contrary the transition from one
to another is almost always gradual, so that iDortions of the plant
covering are difficult to classify. Nevertheless, the formations and
associations are distinct features of the landscape, easily recognizable
by any observer.
' It has seemed best to use the word ''formation *' in the same sense as employed
by the German and most other plant geo-raphers— i. e., to designate ihe
larger assemblages. For more restricted groups, whether composed of one or
many species, the term ''association'' is to be preferred. The nearly ejuivalent
German word "Verein"' is used as a translation of the Danish "Sanifuud" in
one of the most important works on the subject (Warming, Lehrbuch) for the
larger assemblages or formations; but, in the want of a better English word it has
been thought expedient to employ '' association *' for the more restricted assem-
blages, which are peculiar to each biogeographical area. While the ft^rmations are
purely ecological elements which recur in the strand vegetation of other regions,
being for the most part closely dependent upon topographical features, the asso-
ciations are often quite local; and owe much of their character to the particular
groups of species which compose them.
' It is not possible to distinguish here several dune formations, such as occur,
for example, on the coast of Virginia.
_^70 THE PLANT COVERING OF OCUACOKE ISLAND.
SAND-STRAND VEGETATION.
TREELESS, OPEN FORMATIONS.
BEACH FORMATION.
This forination occurs along Pamlico Sound, occupj'ing the flat or
gently sloping sandy beach, especially toward the lower end of the
island. The species are almost all herbaceous and usually form an
open vegetation, leaving much of the soil uncovered. The most
abundant is Croton maritimus, which sometimes grows rather closely,
excluding other species. By reason of its silvery-gray color, due to a
close, stellate, scale-like pubescence, it is one of the most conspicuous
plants of the island. It is usually stout and often much-branched.
Another noteworthy plant is Physalis viscosa, a perennial herb, Avith
slender roots, sometimes 1.5 meters long, creeping near the surface of
the sand, and sending up at intervals short leaf}' shoots. Its color
varies from green to gray with the density of its covering of branched
hairs. An interesting feature of this formation is the occurrence in
places of diminutive thickets onl}" 1 to 3 decimeters high, composed
chiefly of Ilex vomHoria {I. cassine of. authors), Zanthoxylon cJara-
herculiSy Juniperus virginiana, with leaves only of the spreading form,
and Opuntia pes-corvi, with its long spines. Among other species
belonging to the beach formation, there are of annual herbs En-
pliorhia polygonifoUa, Triplasis purpurea, a canescent form of Sola-
num nigrum,, a large-fruited Xanthium, and Salsola kali, the last
being the most abundant; of perennial herbs Teucrium imsliii, with
slender stolons and white-tomentous lower leaf surface, Chloris
petraea, with decumbent culms, rooting at the nodes, Panicum neu-
ranthum, and occasional!}' CaprioJa dactylon {Cynodon dadylon
Pers.); of woody plants Buhus trivial is and Smilax boua-iwx oecnr
here and there, with prickly stems trailing over the sand.
DUNE FORMATION.
Open dunes are occupied chieflj^ b}' the handsome sea oats, Uniola
paniculata, the most characteristic strand plant of the Southeastern
States. The low, rounded dunes Avhich rise from a bare pebbly
shingle on the ocean side of the island, and here and there in the
tiiidst of the tidal flats, support no other vegetation. The leafy
shoots of this grass are iDroduced in great abundance, but flowering
branches are much less numerous.^ Mulilenhergia filipes is abundant
on and among the dunes, its delicate purplish panicles, swaj-ing with
the lightest breath of air, ]3resenting a most beautiful appearance.
It is almost the only cespitose plant of the island, and grows in
tufts that are sometimes 3 decimeters in diameter. Rather small
' In this respect the Uniola resembles Ammophila arenaria, which takes its
place farther north.
TREE FORMATION. 271
plants of Yucca gloriosa, with fleshy rootstocks often exposed by the
shifting of the sands, are frequent on the lesser dunes. The sinjjjle
specimen of Yucca aloifolia observed was over 2 meters high, with
stem branched several times above the ground. Botli species have
exceedingly hard and sharp spinous leaf tips. On some of the liiglier
dunes depauperate plants of the shrubby il/?/rica caroVniensiii^ mostly
onl}^ 3 to 6 decimeters high, associate with the Uniola. Of secondary
importance in this association are two perennial grasses, Paniruyyi
amarurn minus and Spartina patens (juncea); as well as a probably
biennial thistle, Carduus spinosissimus (Cnicus horridulus) ; and
several other herbs, among them the white-sericeous Oeuothera humi-
fusa and Croton maritimus.
EVERGREEN TREE AND SHRUB FORMATIONS.
TREE FORMATION.
Scattered over the island, but preferring the higher dunes which
occupy its inner side, are small groves of live oak, Quercus virgin tana
(Q. virens), either in pure association or mixed with some other trees.
The oaks are usually 6 to 9 meters high and 3 (rarely 7^) decimeters
in diameter. Those on the northern edges of the groves have trunks
strongly inclined toward the south, and, as a consequence of the deiUi-
dation of the branches on the windward side, the whole crown of
foliage lies to leeward of the axis. One could not desire a better
indication of the prevailing direction of strong winds in the region.^
The branches, gnarled and twisted, are clad with numerous lichens,
chiefly Usnea barbata, and with occasional small wisps of Spanish
moss {Tillandsia usneoides), which evidently maintains but a precari-
ous foothold on the trees of this wind-exposed island.
Altogether the aspect of the groves is rather weird and somber.
Often associated with the oaks are small trees of Mijrica cerifera, Zan-
ihoxyluin clava-Jierculis and Ilex vomitoria, all of about the same maxi-
mum size (G meters high and 2 decimeters in diameter), and occasionally
Ju7iiperus virgimana, which rarelj" attains a height of *J meters and a
diameter of 3 decimeters. Lianas are sparingly represented by S)n ila.v
hona-nox, Vitis aestivalis, and Rhus radicans, all three species some-
times attaining considerable size and climbing to the tree tops. The last
is, however, usuall}^ of the creeping form, with the main stem under-
ground. The herbaceous members of this association are, in the
smaller groves, chiefly plants characteristic of the open strand, Cldoris
'All the specimens of live oak seen were apparently of considerable a2re. Seed-
lings were few or none, and no acorns were observed. It is probable that instead
of increasing, the oak is here holding its ground with difficulty. So highly are the
trees valued as wind-breaks by the inhabitants that none are felled, all fuel being
brought from the mainland. The rounded shrubby form of this plant, common
elsewhere on the coast, was not observed on Ocracoke.
272 THE PLANT COVERING OF OCRACOKE ISLAND.
petraea, Physalis viscosa, Diodia teres, etc., and the difference in soil
and light is not sufficiently great to cause any apparent modification
in the plants. In larger groves, where the light is more diffused and
some humus collects, Oplismeniis setarius ^ covers the ground with its
creeping stems, associated with such normally shade-loving species
8is Sanicula sp.y Aspleniuni platyneuron {A. ebenoides), Uniola laxa
(U. gracilis), Panicinn laxiflorurn and two mosses, growing on the
ground, Brymn argenteum and Rhynchostegium serrulatuni.
THICKET FORMATION.
Thickets of I/ex vomitoria, by far the most abundant woody plant
of Ocracoke Island, often cover the low dunes, especially near the
inner side of the island. The plants are here usually 10 to 20 deci-
meters high, with short, rigid, thorn-like branches, light-gray bark,
thick evergreen leaves and bright scarlet berries. The branches are
often shaggy with lichens, notably Ramcdina montagnei. Occasion-
ally the Ilex gives place to small, dense thickets of Myrica carolinen-
sis, sometimes 4^ meters high. This formation corresponds in a
measure to the "Maquis" or "Garrigues" of the western Mediter-
ranean region.^ The herbaceous species that have established them-
selves among these shrubs are chiefly such as are most abundant on
the beach and open dunes. Two thin-leaved, shade-loving herbs are
occasional, Fariefaria dehilis with weak, much-branched stems, and
Melotliria pendida, with twining stems.
SALT-MARSH VEGETATION.
CREEK-MARSH FORMATION.
Salt marshes fringe all the small creeks and ditches that intersect
the lower part of the island, and sometimes cover broader tracts imme-
diately bordering the sound Avith a growth that is almost everywhere
dense and reed-like. 'I'wo rather sharply defined belts are distinguish-
able along the larger creeks, an outer, covered chiefly with Spartlna
stricta, and an inner, where Juncus, roemerianus predominates. The
latter alone occupies the small creeks and ditches which are farthest
from the beach.
SPARTINA STRICTA ASSOCIATION.
The Spartina prefers the edge of open water, where it is in large
part submerged at high tide. It has a light, yellow-green color dur-
ing the growing season, but is brown and discolored much of the year.
The stems are usually about 6 decimeters high. Scdicornia herbacea,
often bright red and conspicuous, grows rather abundantly with the
' In southern Mississippi, also, I found this species growing only in the shade of
Qiiercus virginiana.
2 Compare Grisebach, Veg, der Erde, vol. 1, pp. 294, 328, etc.
SALT-MARSH VEGETATION. 273
grass.^ Distichlis spicata {D. maritima) usually accompanies this
association, but is not of primary importance.
JUNCUS ROEMERIANUS ASSOCIATION.
The Juncus roemerianns association occupies mucli more ccround
than that of Spartina, and comprises a much larger number of species.
It is best developed on land that is merely wet a great part of the time,
and covered with, at most, only a few centimeters of water at high
tide. The Juncus is of a dark-green color, and usually reaches a
height of about 1 meter, making a dense growth of stiff, sharp-
pointed stems and leaves. Among the secondary members of tliis
association certain grass-like plants occur locally in some quantity.
Notable are Chaetochloa iniberhis perennis, with weak, slender culms
from short, knotted rootstocks, preferring the borders of the niarsli,
and Tijplia laiifolia^ usually standing in water of some depth. Spar-
tina patens {8. juncea) is occasional, the salt-marsh form being smaller
and more slender than that which grows upon the sand strand. Pas-
palum distichum and Distichlis spicata are also met with in more open
places among the Juncus.
Compositae, with mostly rather succulent leaves, are conspicuous,
especially near the margin of this association. Aster tenuifolius, a
slender rush-like perennial species whose few branches terminate in
solitary, rather large heads with showy white rays, is less abundant
than the related Aster subukitus, a much-branched, often rather stout
annual Avith numerous inconspicuous'heads. SoTidago sempervirens
and Baccliaris halimifolia s^re most at home on the edge of the Juncus
growth. Both are showy plants, the latter with bright white pappus,
the former with a golden-yellow panicle. Borrichia fridescens, one of
the most characteristic i^lants of the strand, ]3refers comparatively
open spots where the ground is merely wet. It has a stout stem,
usualh^ 3 to 6 decimeters high, thick whitish leaves, and yellow sun-
flower-like heads. Iva fridescens is the most abundant composite of
the marshes, almost always associating with the Juncus. Two climl)-
ing plants, Galactia volid)ilis {G. pilosa) ii\\(\ Vincetoxicum palustre,
a glabrous, narrow-leaved asclepiad, occur near the edges of the marsli,
twining around the stems of the rushes and other plants. Atriplej-
hastata is occasional in similar situations. Even Ilex voniitoria some-
times strays into the marsh, growing among the Juncus as a hnv
straggling shrub.
Somewhat different is the assemblage of species about the small
pools that frequently interrupt the growth of Juncus roemerianus.
'Likewise in southwestern France, Spartina stricfa and Salicornia herhacea
form the outermost association in soil that is submerged at high tide. (Conte-
jean, Geogr. Eot., p. 56.) According to Warming (Lehrlmch. p. 307) Salworuia
herhacea grows unmixed with other species as the outermost embryophylic vegeta-
tion on the eastern shores of the North Sea. S2)artina atrieta does not range so
far north in Europe.
2965 2
274 THE PLANT COVERING OF OCRACOKE ISLAND.
Their borders are the favorite habitat of a characteristic malvaceous
plant, Kosteletzhya virginica, which has rather thin, pubescent leaves
and large rose-colored flowers. AVith it grow a species of Rnmex,
Ipomoea sagittata, Solidago semper virens, Cladium effusum (a stout
sedge with sharply saw-edged leaves), Panicum ivalteri, and, very
conspicuous where it occurs, Andropogon glomeratus {A. macrourus).
In the shallow water of these pools grows Monniera monniera {Her-
pestis monniera H. B. K.) in its aquatic, partially submerged form
with elongated stems, as well as Ammannia hoehnei, Phichea ccnn-
pliorata, and a species of Eleocharis.
DUNE-MARSH FORMATION.
A low, rather scanty vegetation covers limited areas of wet sand
which fringe the reed marsh, separating it from the dry strand, and
also occurs here and there in depressions among the dunes. The
most characteristic species are the terrestrial form of Monniera vion-
nier a ^yith short internodes, and Lippia nodiflora, both having repent
stems rooting at frequent intervals and leaves usually appressed to
the ground. In the case of Lippia, however, the leaves are sometimes
nearly vertical in strong sunlight, giving the plant a peculiar appear-
ance. Each of these species sometimes occupies small tracts to the
exclusion of other vegetation. They usually grow together, however,
and in association with Hydrocotyle umhellata, Centella asiatica, and
Diodia virginiana, all small plants with creeping or prostrate stems.
Among the dunes Lippia and Herpestis sometimes play a less impor-
tant part, and an assemblage of species, some of which are not nor-
mally halophilous, covers the ground. Of these Juncus dichoiomus,
J. scirpoides, Scirpus americanus {S. piingens), Trigloch in striata, and
Mikania scandens are more at home in saline soils, while Ludwigia
7nicrocarpa, L. alata, Cynoctouuni mitreola {Mitreola petiolata), and
Dicliromena colorata (D. leucocepliala) are character plants of the
fresh- water marshes of the region. Such commingling is perhaps to
be explained by the fact that these hollows among the dunes derive
their moisture largely from the rainfall, while, on the other hand,
siDray-laden winds contribute a certain amount of salt to the soil.
TIDAL FLAT FORMATION.
This is an open formation, occupying the margins of the shallow
lagoon at the lower end of the island, which is under water at flood
tide. The soil is a mixture of silt and sand. A sparse growth of
Sesurium maritimuni (S. pentandrum), Tissa marina {Lepigonum
salinum), and Scirpus americanus forms a characteristic association.
Faspalum disticlimn, with prostrate culms, sometimes 2 meters long,
rooting at the nodes, as well as scattered erect tufts of Fimbristylis
spadicea, were the only other species observed in this formation.
ECOLOGICAL FORMS. 275
PASTURE AND RUDERAL PLANTS.
A oonsidenible area towards tlie lower end of Ocraeoke, (^specially
in and near the village, is covered with a fine turf composed almost
entire!}" of Capriola dactylon, closely grazed by horses, cattle, and
sheep. Here and there over these pastures are scattered groups of
various weeds, notably Cassia occidentalism Sporoholus indicus, and
Solarium carolinense, as well as a species of Xanihium, Bidens hipin-
nata, Chenopodium antlielmiidicum, Ambrosia artimisiaefolia^ Ver-
hascum fliapsus^ etc., all of which have undoubtedly l)een importe<l
into the island b}^ the agency of man. Occasionally, strays from the
indigenous formations are met with here. Fleshy fungi are sparingly
represented.
CULTIVATED PLANTS.
As far as was ascertained, the only plants now cultivated upon the
island are fig trees {Ficus carica), which are planted about dwellings
and freely mature their fruit in this mild climate. Small paper mul-
berry trees {Broussonetia papyrifera) are established in door yards.
According to a statement above quoted, peach trees and potatoes wore
formerly grown. Attempts to cultivate garden vegetables are usually
terminated by inroads of the sea during a gale, which leave the soil
strongly impregnated with salt.
ECOLOGICAL FORMS AND ADAPTATIONS TO ENVIRONMENT.
In considering the i:)hysical environment of plants upon Ocracoke
Island, and the various modifications of the vegetative organs whereby
they are adapted to their medium, it is evident that many of the latter
fall readily into two categories : (1) Adaptations protecting against the
mechanical action of the wind^ and the unstable nature of the soil;
and (2) modifications that assist the plant to increase or conserve its
supply of water. Sand-strand and salt-marsh species alike require
both sorts of modifications, although the latter formation is less
exposed to Avind and the shifting of its substratum. However, n(^t
oidy the vegetation upon loose sand, but that which covers the muddy
bottom of the salt marshes, must accommodate itself to a more or less
incoherent and mobile soil. To the first category are to be referred
most of the noteworth}^ life forms of the island, i. e., those in which
the epharmonic peculiarities of structure (such as are due to tlu'
direct action of the physical environment) extend to the entire organ-
ism. To the second belong chiefly modifications of a part icular organ,
the leaf.
^The exposed position of the island, and its consequent relative poverty in large
woody growth, renders herbaceous vegetation here more than usually subject to
the action of the wind.
NATURAL RESOURCES
276 THE PLANT COVERING OF OCRACOKE ISLAND.
ADAPTATIONS TO THE MECHANICAL ACTION OF THE WIND AND
THE INSTABILITY OF THE SOIL.
A notable characteristic of the vegetation is the prevalence of low
forms. Tall stems (more than 1 meter high) among herbaceous species
which are not grass-like, are almost wanting. Often the stems creep
above or below the surface of the ground and root at intervals.
Lippia nodiflora, Monniera monniera, Capriola dactylon, and Pr/.s-
paliim disfichum have stems creeping upon the surface. These may
be regarded as humble representatives of the Pes-caprae form, which
is so characteristic of tropical strands.^ Species possessing creeping
subterranean stems, from which arise subaerial leaf}^ and flowering
branches, are Panicum amarum minus and Uniola p>aniculata, as well
as many of the salt-marsh plants, notably Juncus roemerianus, Typlw
Jafifolia, and Spartina stricta, whose strong, creeping rhizomes form a
dense sod in the loose mud. In Uniola paniculat a the rootstock is stout
and descends obliquely or almost vertically deep into the sand.
Pliy sails viscosa has a long, slender, branching root, Avhich creeps
horizontally often a distance of a meter or more near the surface, and
originates at intervals erect, leaf 3^ and flowering branches. Teucriurn
nasliii i)ossesses thickish stolons, which arise in the axils of the scale-
like, lowest leaves.
Other species growing on the sands have prostrate stem branches,
which do not root after leaving the main axis. These may be long and
trailing, as in the woody Rubus trivialis, or short and radiating in all
directions from the primary axis as in certain annuals, Diodia teres, D.
virginiana, Jlollugo verticillata, and Eupliorhia polygon if olia, as well
as the biennial Oenothera humifusa. This radiant form,^ as we may
term it, is not so abundant and characteristic here as at other points
along the Atlantic coast of the United States.
The cespitose form is apparentlj^ not well adapted to conditions
upon Ocracoke, for it is well developed only in Mulilenhergia filipes.
The shrubs and trees of the island show the effect of much exposure
to high wind in their short gnarled branches and in the often one-
sided position of their crown of foliage, the last peculiarity being
especially noticeable in the live oak. Here, however, w^e have to do
rather with the direct mechanical effect of the wind than with a pro-
tective modification.
As further adaptations against the coast winds, whose destructive-
ness to tender vegetation must be greatly increased by the quantity
of sand they carry, should be cited the great development of mechan-
ical tissue in the leaves of many species — e. g., Uniola panicuUda,
Juncus Toemerianus, Quercus virginiana — and the strong thickening
of the outer cell walls of, the epidermis, to which is due the hard pol-
' Schimper, Indo-Mal. Strand-flora, p. 78.
■' Schimper (Strand-flora, p. 81 ) describes this form as occurring in the East Iiidian
strand vegetation. ; t:^'^>. ^ .»^.
COLLECTION AND STORAGE OF WATER. 277
ished surface exhibited hy the larger grass-like plants and by the
evergreen leaves of Quercus and Ilex. This last peculiarity is, how-
ever, doubtless primarily induced by the necessity f<jr protection
against loss of water.
ADAPTATIONS FOR PROTECTING THE SUPPLY OF WATER.
Strand iDlants upon Ocracoke Island, unlike deser^^^ plants, are not to
any noteworthy extent equipped with special apparatu.4 for collect ing or
for storing water, if we except the development of water-storage tissue
in several of the salt-marsh species. The obvious reason is the aljsence
of a period of drought, there being at all times a relatively high per-
centage of water in the air and the soil. On the other hand, both
maritime and desert vegetations are characterized by certain pecul-
iarities of structure, especially of the leaves, which are usually-
denominated xerophytic, albeit these are less strikingly developed in
strand plants than in those which inhabit deserts. Such common
points of resemblance are, as isAvell known, due to a common necessity
for i)rotection against excessive loss of water by transpiration from
the leaves, and this despite the abundant supply of water in the
environment of strand plants.
In the case of salt-marsh vegetation it is chiefly the presence of a com-
paratively high percentage of sodium chlorid in the soil water which
necessitates a xerophytic structui-e. Jtist how this salt reacts upon
the life processes of plants and what the precise mode is by which
i:)lants iDrotect themselves against its injurious effects are much mooted
questions.^
^ Con te jean (Qeogr.bot. ,pp.71,94) holds that salt is harmful to most plants; that
it is not indispensable even to strand plants, and that the latter are confined to an
otherwise unfavorable habitat merel}' by their inability to compete in the struggle
for existence with the salt-shunning species of nonsaline soils. That this view is
only partially correct is suggested by the known tendency of halophilous (salt-
loving) species to take up greater quantities of sodium chlorid, even when grown
in nonsaline soils, than do jDlants which are not halophilous.
Schimper (Strand-flora, pp. 2o, 26) attributes to the accumulation of sodium chlo-
rid in the green tissue an injurious effect upon assimilation, particularly upon the
production of starch and sugar. More recently (Pflanzengeogr., p. IOC) he modi-
fies this view, but still emphasizes the importance of a chemical action of the salt
upon metabolism, the synthesis of proteids being the process cliiefiy affectcl.
In order to reduce this deleterious action to a minimum, the accumulation of
sodium chlorid in the tissues must be as far as possible retarded. This is accom-
plished, according to Schimper's theory, by diminishing root osmosis and hence
the volume of the ascending colunm of water holding the chlorid in solution,
this end being secured by means of certain modifications of leaf structure that
reduce the volume of transpired water. Besides this chemical effect, Schimper
also admits a direct physical infiuence which the presence of common salt in the
soil exerts upon the process of osmosis. As Sachs (Landw. Versuchsst. vol. 1, p.
223) demonstrated by experiment, the roots of ordinary plants take ud with diffi-
culty water which holds in solution sodium chlorid as well as other salts nota-
bly calcium sulphate), a difficulty that of course increases with the concentration
2(8 THE PLANT COVERING OF OCRACOKE ISLAND.
Factors in the iDlij^sical environment of sand-strand vegetation
which tend to accelerate transpiration from the surface of the jDlant,
and hence contribute to the necessity for xerophytic structure, are :
1. Exposure without shelter to the almost continual and often vio-
lent movement of air currents, which keep the plant's atmospheric
envelope constantly changing and prevent it from approaching a con-
dition of saturation.
2. Intense light, both direct and reflected from the surface of the
sand. Light, which becomes converted into heat in the chlorophyll
tissue, increases transpiration ^ in proportion to its intensity. Besides
this effect of light, its direct and harmful action, when too intense,
upon the chlorophyll is to be guarded against, and this is probably
effected bj^ some of the modifications which also serve to reduce
transpiration. But in the present state of our knowledge it is imj)os-
sible to discriminate between the respective modifications Avhich
protect the plant against these two effects of light.
3. Great heat during a great part t)f the year. Much more intense
than the atmospheric heat is that which is absorbed by and reflected
from the superficial layer of sand.^
It is probable, however, that the i)resence of a high percentage of
sodium chlorid in the substratum is at least as effective as any of
these causes in bringing about xerophytic structure. This is evident
of the solution. Whether this is equally true of halophilous species is not
established.
L. Diels ( Jahrb. Wiss. Bot. vol. 23, p. 316) doubts that osmosis in plants of saline
soils is sufficiently reduced to account for the absence of accumulations of salt to
an injurious extent in the tissues. He found that salt-marsh plants when trans-
ferred to distilled water showed a steady loss of salt from day to day, although the
impossibility of an excretion of the sodium chlorid as such could be demonstrated.
This author gives a number of analyses of halophilous species which would indi-
cate that in plants of that character the cells are enabled to decompose the
accumulated sodium chlorid, the sodium probably uniting with malic acid, while
the chlorin possibly combines with water and passes off through the roots as
hydrochloric acid. It is known that xerophytic modifications which protect the
plant against excessive transpiration at the same time cause an increased evolu-
tion of tree acids (notably malic acid) in the green tissue, by preventing the
ready access of oxygen and otherwise hindering the exchange of gases between
the plant and the atmosphere. These researches of Diels, if confirmed for halo-
philous plants generally, will prove an insuperable objection to Schimper"s theory
that such plants can prevent an indefinite accumulation of sodium chlorid in
their tissues only by reducing root action and hence transpiration. If we accept
Diels's conclusions, v/e should have to refer the xerophytic structure of halophilous
plants largely to its efficacy in preventing a f re-3 exchange of gases between plant
and atmosphere, thus rendering imperfect the combustion of carbohydrates in the
plant tissues and occasioning the production of considerable quantities of organic
acids, which serve the plant by decomposing the absorbed sodium chlorid.
'Wiesner, Untersuch., p. 506.
2 Volkens (Fl. .^gypt., p. 14) found a difference of from 22^ to 24° C. between the
temperatures of the surface soil and of the atmosphere in the shade near Cairo, in
Egypt, the maximum heat of the sand being 55° C.
MEANS OF REDUCING TRANSPIRATION. 279
when we examiue the siill-inarsh vegetat iuii. Must of the species of
tliat formation, even those wliieh are wliolly or partially submerj^ed
at high tide, possess siieh structure. No plants of th<' North Carolina
strand are more conspicuously xerophytie in structure than Salirornid
lierhacea and Spartina stride. That such structure is closely related
to the ability to take up NaCl in considerable (iuantities is i)nn cd \)y
the fact that certain species which do not naturally inliahit saline
soils, but wdiich possess strongly developed modifications airaiust
excessive transpiration, can absorb that salt in ([uautilics ihai are
fatal to plants not so constituted. ^
For this reason species belonging respectively to the saml si rand
and to the salt marsh of Ocracoke Island are not distinguished in lh<3
following enumeration of the means by which transpiration is i«'<l nc-d.
1. Reduction of the transpiring surface.
(a) Leaves small: Ilex vomitoria ( smallest-leaved of our species of llexj, Gakic-
tia rolubiUs (unusually narrow-leaved form.) ,Vincetoxicinii palast re, Tis.sd marina
(leaves liemicylindrical), Monniera monniera, Lippia xodijiora (leaves notably
smaller than in nonsaline soils), Se.KKvium maritimum, etc. Most of the species
enumerated have small or narrow leaves as compared with the nearest related
inland forms.
(b) Leaves scale-like, their functions transferred to the stem, which is succu-
lent; stem succulents: Opuntia pes-eorvi, Saliconiia licrbacea.
(c) Leaves conduplicate or involute, especially in dry, sunny weather, so that
only the dorsal surface is exposed: All the grasses, and Cladiioa effusnm, Fim-
bristi/Us s2Jadice((, and other sedges. In the f^rasses this characteristic is corre-
lated with the position of the stomata, which lie at the bottom of furrows, espe-
cially on the unexposed ventral surface, and are further protected from air currents
by a network of hairs which line the walls. In Quercua viryiniana the leaf mar-
gins frequently become more or less revolute.
Ul) Leaves iDerfectly terete and in structure little ditferentiated from the stem:
Juncus roemeria n us,
2. Position of the transpiring surface, leaves vertical or nearly so: Many of the
grasses and sedges, Tijplia, Juncus roemeria mis, Friijloehin striata, yonui^ leaves
of Yucca spp., Lippia nodiflora (sometimes), Vincetoxicum palustre (leaves
reflexed) , the Compositae.
'S. Development of protective modifications in the epidermis.
(a) Thickened cuticle: Many species, notably the larger grass-like plants and
woody species with evergreen leaves. A shining upper leaf surface, as in Ih\c
vomitoria, may he of use by reflecting some of the incident light rays, as has been
suggested by Wiesner.
(b) Waxy covering: Panicum amarum, Uniola panicidata, Euphorbia poly-
gonifolia, etc. This character is but slightly developed in the vegetation of Ocra-
coke Island.
((') Hairy covering: Oenothera hnmifusa and Teucriuin )iashii (hairs long,
simple); Quercus riryiiiiana (stellate hairs on the dorsal surface only): Kiisteletz-
kija virginica and Croton maritimus (hairs stehate, scale-like): Phijsidis risco.sa
(hairs forked); BorricJtiafrutescens (youngleaves very densely covered with short
hairs, giving the surface a glistening appearance). Interesting hairs also occur
on other species, but not in sufficient numbers to serve as a protective covering
(except in the leaf furrows of certain Gramineae).
Schimper, Pt^anzenge(igr., \). 0".).
280 THE PLANT COVERING OF OCRACOKE ISLAND.
4. Succulency.
(a) Stem succulents: Opuntia jpes-corvi , Salicornialierhacea.
(b) Leaf succulents: Fncca spp., Tissa marina, Sesuvium mar itimum, Euphor-
bia polygonifolia, Vincefoxicum palustre, Aster subidahis, A. flexuosus, Solidago
sempervirens — mostly salt-marsh species. Not only does the increase in thickness
of the leaf serve directly as a protection against excessive loss of water, but the
thickening tissue consists, in most cases, of colorless, water-storage parenchyma,
which is peculiarly tenacious of its water supply.
5. Structure of the chlorenchyma.
Nearly all the species, of both sand strand and salt marsh, are characterized by
the development of palisade, a compact chlorophyll tissue with cells more or less
elongated at a right ang-'.e to the surface and occupying the exposed face or faces —
i. e., the ventral face in bifacial leaves, both faces in such as are isolateral. Such
tissue is believed to have, among other functions, that of protecting against ex-
cessive loss of water the remainder of the leaf (the interior, or the lower face, as
the case may be) , which is usually occupied by less compact tissue.
6. Aromatic, volatile oil.
An oil of this character is secreted by the species of Myrica. It has been sug-
gested, although the idea needs substantiation, that the possession of such oils
affords protection againsr excessive loss of water by the formation about the plant
of an envelope, which is less pervious to heat rays than is ordinary air. At any
rate this is a frequent attribute of plants inhabiting very dry regions.'
Not to be interpreted as affording protection against excessive
transpiration, yet perhaps largely dne to the inflnence of conditions
that necessitate such protection, is the develoinnent of short, rigid,
almost thornlike branches {IJex vomitoria) and of prickles and spines
(Smilax, Biihus trivialis, Opnntia, Zanthoxylum, leaf apices of the
species of Yucca). Probably the depauperate form assumed by some
of the woody species when growing on the beach is similarly explicable.^
Strong thickening of the under-ground parts for storage of reserve
food materials does not occur in many si)ecies. The only notable
cases detected were Smilax hona-nox (rootstocks with tuberous thick-
enings), Yucca spi^. (rootstocks large, fleshy), and KosteJetzkya vir-
gin ica (root stout, Avoody, vertical).
ANATOMY.
In almost all cases the histological structure of the leaf alone is
here considered, that being the organ which shows most plainly
adaptations to certain factors of the environment, notably those
wiiich affect transpiration. The general peculiarities of leaf anatomy
in the vegetation of the sand strand and of the salt marsh, respec-
tiveh^, are first enumerated, and the resemblances and differences of
plants of the two formation classes are liointed out. Several of the
more important species of each category', in all thirty-two, are then
^Haberlandt, Pflanzenanat., p. 325. Volkens, Fl. ^gypt., p. 46.
'^A like depressed habit is characteristic of shrubs growing above the limit of
trees in high latitudes and altitudes. It is usually attributed to exposure to strong,
dry winds, which is probably the chief factor in its development on the beach of
Ocracoke Island.
PROVISIONS FOR CONSERVING WATER. 281
taken up and described in sj-stematic order. Tables sliowini,^ wlial
are believed to be the characters that are most iinportanl from an
ecological point of view have been prepared for tlie two <^m-()iii)s of
species. For a nnmber of species the material studied was not
obtained npon Ocracoke Island, but from simihir situations on the
coast of Virginia, and in all such cases tlie source of tlie spefim«Mis
used is mentioned. In some cases comparisons are made with rehited
species, usually from other formations, in order to make clear the
differential characters of the strand species.
In a great majority of the sand strand plants the leaf is bifacial,
the two species of Yucca being the only exceptions noted. In some
species this specialization is imperfect, as in Oenothera humifusd. \n
other cases the differentiation of the two sides of the leaf is com-
plete, as in Quercus virginiana. In most cases the leaf is thick as
com]3ared with the same organ in related nonmaritime species. Good
examples are the evergreen, leather}^ leaves of Quercus virfjiniana
and Ilex romltoria, as well as the leaves of the two grasses, Uniola
paniculaia and Panicuin amarum. A stronglj^ thickened cuticle is
. an almost invariable character, and this is conspicuously wrinkled in
a few species. The lateral walls of the epidermis cells are undulate
in four species, viz, the comparatively thin-leaved Cliloris petraea,
Teucrium iiasliii, and Phy sails viscosa, and tlie thick-leaved Ilex
vomit or la.
Half of the species have stomata on both leaf surfaces, but in every
such case they are especially protected — in the grasses by being sit-
uated in furrows; in the species of Yucca by being deeply sunken,
and in Physalis, Oenothera, and Croton b}' a covering of hairs. In
the wood}^ species they are always on the dorsal or lower surface only,
and in Quercus virginiana they are further protected by a hairy cov-
ering (as also in the herbaceous Teucrium nashll).
Hairs form a dense, i)rotective covering on both leaf sui-faecs of
Oenothera, Croton, and Physalis, which species have stomata on both
surfaces: only on the dorsal surface in Quercus and Teucrium, agree-
ing with the i^osition of the stomata on that surface only. In Quercus
and Croton the hairs are pluricellular and stellate; in Physalis iIh.n
are irregularly branched; in Oenothera and Teucrium they are elon-
gated, unbranched, and unicellular. Teucrium also possesses slioi-t,
glandular, cai)itate hairs.
The chloroi3h3dl tissue is homogeneous in the monocotyledons of
the sand strand, while in the dicotyledons it is more or less difTereii-
tiated into palisade on the ventral side of the leaf and pneumatic
tissue on the dorsal side. The palisade is mostly quite compact, but
never of more than 3 and usually of only 1 or 2 layers.
Colorless parenchyma, which probably performs the function of
water-storage tissue, occurs in consideral)le quantity only in the
grasses and the species of Yucca.
282 THE PLANT COVERING OF OCRACOKE ISLAND.
Stereome occurs subepidermally (especially in the leaf margins) in
the Gramineae only. In most of the species of the sand strand, how-
ever, it is found as a support to the mestome bundles. These are
furthermore reinforced by hj'podermal collenchyma or collenchymatic
tissue in most of the dicotyledonous species, this tissue probably serv-
ing as a protection against loss of water by evaporation from the
vessels.
The sand-strand grasses deserve further mention with reference to
their leaf structure. It belongs to a type of which Chloris petraea
exhibits one extreme and Muhlenberg m filipes the other — the type
exhibited by most grasses of deserts and steppes. The salt marsh
Spartina stricta exhibits a wholly similar arrangement of tissues.
The margins are more or less conduplicate or involute when the
supply of water is small, becoming flat when moisture is plentiful,
except in the leaf of Muhlenhergia filipes, which is conduplicate, with-
out power to unfold, and appears as if terete. The result of this
adaptation is that in dry, sunny weather only the dorsal leaf surface
is directly exposed to the air and light. In Panicum amarinn and
Chloris ]petraea the movement is effected by true bulliform cells, while
in the other grasses (except, of course, Muhlenbergia) the function is
probably performed by certain large but otherwise undifferentiated
cells of the epidermis, which may be regarded as undeveloped bulli-
form cells.
The stomata lie near the bottom of deep longitudinal furrows and
usually occur more abundantly on the protected ventral surface of the
leaf, but in Chloris petraea only on the dorsal surface. The walls of
these furrows, in Muhlenbergia, Uniola, and Spartina patens, are lined
with unicellular, simple, prickle-like hairs, which doubtless hinder the
escape of moist air.
Subepidermal groups of stereome occur in the leaves of all the
grasses and in the margins of all except the Muhlenbergia. In this
great development of strengthening tissue we have in all probability a
protection against the mechanical effects of the wind, to which strand
grasses are much exposed.
The chlorophyll tissue is in every case radially arranged in single
layers around or at each side of each mestome bundle. In most cases
the adjacent cells of the parenchyma sheath also contain chlorophyll.
Each mestome bundle is surrounded by a mestome sheath in all the
species except Uniola and Muhlenhergia, and this by a large-celled
parenchyma sheath. The parenchyma sheath without the mestome
sheath occurs in Muhlenbergia.
Among the species of the salt marsh which were examined, the
isolateral type of leaf prevails, Kostelefzkya virginica and Lippia
nodiflora being the only exceptions, and in these the leaves are but
imperfectly bifacial. In Juncus roemerianus the leaf is terete.
Thick leaves are also the rule in this formation class, although less
TISSUES. 283
strikingly so than in the sand strand, because of the lack, of hirge
woody j)lants; and the thickened leaf is usually of a soft, succulent
character rather than leathery. A majority of the species show a
conspicuously thickened cuticle, which is strongly wrinkl«Ml in 7 out
of 15 of them and granular or warty in 3 more.
Corresponding to the isolateral structure of most of tlu- Icax <-s we
find stomata on both surfaces in 12 si^ecies; on tho whohi circumfe'r-
ence of the terete leaf of Ju)icusroeinerin?ii(.s; confined to tlie ventral
or upper surface only in SjKiriina stricfa und BorrirliUt frufescens.
In 4 species the guard cells are slightly prominent, in 7 level with tlie
epidermis, in 3 slightly sunken, in 1 {Spariirta slricta) situated in*ar
the bottom of deep furrows. Hairs occur in l)ut 5 species. In l5or-
richia alone they form a dense covering, nearly every epidermal cell
appearing to have developed a iDluricellular, thin-walled liair by
tangential division. It is evident that we have in this case an admi-
rable j)rotection against excessive transpiration.
Stereome occurs in notable quantity only in the leaves of SiKiriina
stricta and Juncus roemerianus. In both it is subepidermal as well
as about the mestome bundles. Juncus roemerianus is especially
noteworthy for the strong development of both peripheral and axial
stereome groups. Ilj'podermal collenchyma, or collenchyma-likc
tissue, occurs opposite the veins in two-thirds of the species examined.
The chlorenchyma is homogeneous in all but '2 species, and in 1 of
these, Lippia nodiflora, the differentiation is slight. In nearly all
the si)ecies it consists of comj)acu palisade, interrui)ted in several
cases by ducts or lacunes. In the leaves of most of the species there
are only 2 layers on each side of the isolateral leaf, but in Ju7irus
roemerianus the bands of Avell-developed palisade are 5 or 6 layers
thick. In several of the Comj)ositae, all decidedly halophilous species,
the ends of the palisade layers where they abut upon the midvein
converge toward the vein and appear as if radiating from it. This
was observed in Iva frufescens, Baccharis halitnifolia, and Aster
teiiuifolius, and may occur in other species. The significance of this
arrangement is not known. It is cited by Warming^ as a lialophytic
character. SjKirtijia stricta agrees in the arrangement of its chlo-
rophyll tissue, as in other respects, with the sand-strand grasses.
Colorless parenchjnna, which i^robably serves for the storage of
water, is present in greater or less quantity in S species, occupying
the greater part of the interior of the leaf in 4, while occurring only
about the veins in the others. In l>oiricliia, which is one of the most
xerophytic in structure of all the salt-marsh species, this tissue is
best developed. It is also well exemplified in 'Tissa marina.
In the 3 salt-marsh inhabiting monocotyledons examined — Triylo-
cliin striata, Sjoartina stricta, and Juncus roemerianus — each mes-
' Halofyt-Stndier, p. S50.
284 THE PLANT COVERING OF OCRACOKE ISLAND.
tome bundle is i)rovided with a well-marked mestome sheath and,
outside that, a parenchyma sheath.
When Ave compare the species belonging to the two formation
classes, sand-strand and salt-marsh, we find that a majority of both
have several characters in common, all of which are distincth' xero-
phytic and are usually interpreted as protecting the leaf against
excessive transpiration as well as the effects of too intense light.
These are : Thickened leaves, thickened cuticle, and development of
the chlorophyll tissue as compact palisade on the most exposed sur-
face or surfaces.
More numerous, however, are the differential characters. The
leaves of the sand-strand species are usually bifacial, with stomata
only on the dorsal surface or, if on both surfaces, protected by a hairy
covering or lying in deej) furrows; and the palisade is situated on
the more exposed upper or ventral side of the leaf. The salt-marsh
species, on the other hand, have mostly isolateral leaves, vertical or
nearly vertical in i^osition, with stomata and i)alisade on both sur-
faces, and (with one exception) lacking the dense hairy covering.
Conformably, the most common grass of the salt marsh, Spartina
stricta, otherwise so similar in leaf structure to the dune form of
>S'. patens, has no hairs lining its stomatal furrows. The cuticle is
wrinkled or warty in many more salt-marsh than sand-strand species.
AVater-storage i3arenchyma, which is notably developed in the sand-
strand vegetation onl^^ in the monocotyledons, is present in a majority
of the salt-marsh plants of the most diverse relationship.
Corresponding to their growth in usually open formation, and con-
sequently greater exposure to the wind, the sand-strand plants show
a much stronger development of stereome than do the salt-marsh
species. On the other hand, the latter are better i^rovided with hypo-
dermal collenchyma, or coUenchymatic tissue, opposite the veins; but
this ma}^ be more imiDortant as a protection against loss of water
than as a mechanical strengthening tissue.
It should be emphasized that not onl}^ the peculiarities common to
plants of the two formation classes, but likewise most of their respec-
tive differential characters, are really of a xerophytic nature.^ In
some cases, however, a different means has been employed by sand-
strand species on the one hand and by salt-marsh species on the
other to secure the same end — protection against excessive transpi-
ration and the harmful action of too intense light.
' In his most recent paper on the subject. Warming (Halofyt-Studier, p. 235)
writes: "It is not possible, from the investigations here described, to draw any
clear distinction between characters which are truly xerophj^tic and such a 3 are
truly halopliytic, if any really exist." Schimper (Pflanzengeogr., p. 99) also holds
that halophytes can not be distinguished as a class from xerophytes, since the
principal object'of the peculiarities of structure observable in plants growing in
saline soil, however moist, is the reduction of transpiration, just as it is in plants
snrrounded by a physically very dry soil and atmosphere.
ANATOMY OF SAND-STRAND SPECIES. 285
SPECIES OF THE SAND STRAND.
Panicum AMARUM Ell.^
Leaf bifacial, strongly involute when dry, midrib not prominent on
the dorsal surface and not much so on the ventral surface, shjillow
furrows (deepest each side of the midrib), with broad and rounded
intervening ridges on the ventral surface, corresponding to very
slight depressions on the dorsal surface.
Epidermis: Ventral, similar to the dorsal, but willi iliinner outer
cell walls; stomata at each side of the group of 3 thick-\vall(Ml 1) uni-
form cells at the bottom of each furrow; hairs none. Dorsal with very
thick, porous outer cell walls, 1 or sometimes 2 short cells alternating
with long ones, except in the rows containing stomata; stomata lying
in the shallow furrows, with walls of the guard cells much thickened;
hairs none.
Subepidermal stereome in large groups above and below the midrib,
that above separated from the hadrome by several layers of thickish-
walled, colorless parenchyma; smaller groups above and below the
other nerves; strongly developed in the margins.
Chlorophyll tissue (palisade) arranged radially in a single layer
about each mestome bundle, almost completely encircling the smaller
nerves, interrupted above and below the larger ones, each 2 neighbor-
ing rows of palisade separated by a single layer of colorless paren-
chyma; chloroi)hyll likewise occurring in the cells of the parenchyma
sheath which adjoin the palisade.
Mestome bundles surrounded each by a mestome sheath wliich, in
the larger veins, has all, or nearly all, of its cells with walls (especially
the inner) strongly thickened ; mestome sheath in turn surrounded
by a large celled i^arenchyma sheath; mestome parenchjnna in a single
layer of thick-walled cells sei^arating the hadrome from the leptome.
MUHLENBERGIA FILIPE8 M. A. Curtis."
Z/ea/(fig. 33)condui)licate without power to unfold, appearing as if
terete, slightly asymmetrical, margins almost meeting al)ove the mid-
nerve, and hence only the dorsal surface exposed. From ihe sliuhi
opening between the margins to the uiidrib extends a narrow iissui-e,
with lateral furrows between the larger nerves reaching more than
halfway to the dorsal surface of the leaf. The ridges al)ove the
mestome bundles between these furrows arc broad and rounded at
apex, except that of the midnerve, which is narrowed outward (hence
conical in cross section). On the dorsal (outer) surface are narrow,
'The typical form of this species was not observed upon Ocracoke JslaTid. but
the leaf of var. mi)iiLs Vasey & Scribner, which was collected there, c-orrespon«ls
in every detail to that of the type.
- Compare Volkens's figure and description of .lr/.s//f/</ t'///(//(t (Fl. vEi;ypt.,pp.
49, 150, t. 10, ff. 4 to 7).
286
THE PLANT COVERING OF OCRACOKE ISLAND.
slit-like furrows between each 2 nerves (hence 2 to every ventral
furrow), opening into wider air spaces with stomata at each side of
the bottom. Stomata also oc-
cur near the bottom of the ven-
tral furrows, but are there less
numerous.
Epidermis: Ventral (fig. 34)
with cell walls thinner than on
the dorsal surface, many of the
cells extended into straight or
curved, spreading, unicellular
hairs which line the main cav-
itj' and lateral furrows with
a dense cross work, and are
larger, thinner -walled, and
more slender than those which
occur on the dorsal surface;
bulliform cells none. Dorsal
(fig. 35) with smaller cells, the
outer Avail and cuticle so
greatl}^ thickened as nearly to
equal the cell lumen, the areas \ying above the subepidermal strands
of stereome having single rows of short cells which alternate with
several rows of long ones; many of the epidermal cells extended into
short, stout, pointed, thick-walled, unicellular, appressed, prickle-
like hairs, which line the furrows.
Subepidermal stereome: None on the
ventral side of the leaf and in the margin;
Fig
-Muhlenbergia fil ipes—triLnsYerse section of
leaf. Scale 75.
'Fig. ^.—MuhJenbergia fiUpes—
ventral epidermis of leaf.
Transverse section, showing
the hairs. Beneath the epi-
dermis are layers of colorless
parenchyma. Scale 400.
Fig. 35.- Muhlenbergiafilipes— dorsal part
of leaf blade. Transverse section show-
ing the epidermis (Ep.), stereome (St.^^
and rather thick- walled colorless paren-
chyma (Pa.), which borders on the
mestome bundle. Scale 400.
on the dorsal side in the form of flattened supporting strands^
beneath the mestome bundles, passing gradualh' into the often
^" Abgeplattete Trager," Schwendener, Mechan. Princ, p. 40.
ANATOMY OF MUHLENBERGIA.
287
separates it tVom ili
lliick-walled, colorless parenchyma wliicli
tome sheath.
Clilorenchyma (fig. 3G) consisting of small, branched cells wiih smal
i-adially arraii,Li<'<l ahout racli
-Zy^n/.
_^ Too.
Fig. 36.—Muhlenbergia filipes— portion of
mestome bundle. Transverse section
of blade, showing a part of the leptome
(Lept.), the parenchyma sheath (P),
the chloreuchyma (Mes. Kand the col-
orless parenchyma (Pa.) between the
mestome bundles. Scale OUO.
intercellular spaces in a single layev
mestome bundle, Ij'ing only at the sides
of the larger bundles, but extending
in horseshoe form around the ventral
(hadrome) portion of the smaller ones.
Parenchyma sheath of the mestome
bundles, where adjoining cliloren-
chyma, also containing chlorophyll.
Colorless parenchyma (fig. 86) occu-
pying the larger ventral ridges (over
the larger mestome bundles), and in 2
or 3 rows of cells between each 2 nerves,
extending from the ventral to the dor-
sal furrows. Also in 1 or 2 rows sepa-
rating the chloreuchyma from the pa-
renchyma sheath of the smaller bun-
dles.
Mestome bundles (fig. 36) with a large-
celled parenchyma sheath; mestome
sheath none, but mestome parenchyma
with cell walls (especially the inner) much thickened, surrounding tlie
larger nerves, simulating a mestome sheath; many of the companion
cells in the leptome very thick- walled.^
' The two species of Muhlenbergia most nearly allied to 31. filipes are J/, capil-
laris (Michx.) Kuntli and M, tricUopodea (Ell.) Chapm. Chapman regards .1/.
filipes as a variety of M. capillaris, but the striking histological differences, together
with good morphological characters, show that in M. filipes we have a perfectly
valid species.
A comparison of the leaf anatomy of the three forms gives some very interesting
results:
(a) M. capillaris is a plant of dry sandy or rocky (eugeogenous) soils, but the leaf
shows only feebly the strong xerophy tic structure of 21. filipes. Material from ( t reat
Falls, Md. , was studied. Leaf thinner than in M. filipes, conduplicate when dry, but
flat when well supplied with water. Ventral face not furrowed, furrows on the
dorsal face extending nearly halfway through the leaf, with stomata at bottom.
Epideriiiis much as in M. filipes, but with bulliform cells between each 'J nerves;
hairs much fewer than in filipes, all short, thick- walled, pointed, and prickle-like,
occurring on the ventral face only above the nerves, on the dorsal face lining the
stomata-bearing furrows and there thicker- walled, with hardly perceptible lumen.
Subepidermal sfereome in flattened supporting strands al)ove and below rhe
mestome bundles, from which they are separated by thickish-walled, colorless
parenchyma; and also in the leaf margins.
Chloreuchyma as in filipes, but entirely surrounding the smaller bundles, inter-
rupted by colorless parenchyma above and below the larger (mes. Also much
chlorophyll in the cells of the parenchyma sheath which adjoin tiie chlorenchyma,
Mestome bundles with no true mestome sheath, but mostly surrounded by a sin-
288
THE PLANT COVERING OF OCRACOKE ISLAND.
Spartina patens (Ait.) Muhl.^
Leaf involute when dry, deeply furrowed between the nerves on
the ventral face, high, broad, rounded ridges separating the larger
gle row of mestome parenchyma with cell walls thinner than vafiUpes and evenly
thickened; mestome parenchyma aJso in a single layer between hadrome and lep-
tome, and, with a few of the companion cells of the leptome, isolated or in groups
of 2 or 3, very thick- walled.
(5) Muhlenhergia tricliopodes is a plant of low, often moist, pine barrens in the
Gulf strip of the Austroriparian area. The example here described was collected
in Mississippi. It is in several histological characters intermediate between capil-
laris ^-ndi filixjes, although morphologically the most distinct of the 8 species.
Leaf conduplicate when dry, nearly flat when supplied with abundant moisture.
Ventral surface with only the 2 or 3 nerves nearest each margin prominent and
separated by deep furrows, the otliers, including the midnerve, barely i)rojecting.
Dorsal surface with narrow and rather deep furrows between the nerves.
Epidermis: Ventral with sing'e rows of short cells alternating with several rows
of long ones; hairs, chiefly in the furrows, shorter, stouter, and thicker- walled than
iufilipes; bulliform cells much as in capillaris, rather thick- walled. Dorsal with
rather thick- walled cells (less so than in^Zipes), single, quadrangular (from above),
short ones alternating with longer ones; hairs short, stout, thick-walled, prickle-like.
Suhepidermal stereome rather more strongly developed than in capillaris and
jilipes, in flattened supports above and below the mestome bundles (hence at
summit of the ventral ridges), strongest on the dorsal side, where it interrupts
the parenchyma sheath of the larger nerves: also in the margins.
Clilorencliyma with cells as in filipes, radially arranged in single layers about
the bundles, entirely encircling the smaller ones, in the larger ones perpendicular
to the leaf surface and extending to the stereome at the summits of the ventral
ridges (as in Spartina strict a and Uniola panicidata)-, parenchyma sheath and
the large parenchyma cells above the mestome bundles also containing chlorophyll
where they adjoin the smaller-celled chlorenchyma.
Colorless parenchyma (rather thick- walled) filling the interior of the ridges, and
in a single row of large cells between each 2 nerves, separating their respective
bands of chlorenchyma.
Mestome bundles withont a true mestome sheath, but the larger ones surrounded
by a layer of mestome parenchyma which is much thicker-walled than in the 2
related species; around the smaller bundles the mestome parenchyma thinner-
walled and interrupted by 2 large vessels of the hadrome; mestome parenchyma
also in t layer between hadrome and leptome, as in the other 2 species.
The important leaf characters of these allied species of Muhlenhergia may be
tabulated thus;
[The sign x indicates presence of character.]
Species.
1
It
1
3
^1
tc.5
p.
1
6
|.3
i1
II,.
a o
m
ii lii
1
1
^1
a®
o >
p.
?2
u
13
s
«2
2 H
s
p
3 o s -:; c c
^^J-^^ z> a-^^
P
<
Q
«
^•-^
S
ffl
ffl
^
02
^ ,^
Cai3illaris
X
X
X
X
X
X
X
X
X
■ 1 X
Trichopodes
X
X 1
X
X
X
X
I
' Compare the figure of S. versicolor in Duval- Jouve, Etude Anat., ^>/. lC,jhj.
ANATOMY OF SPARTIXA. 289
fill-rows, which aw L'-clcrt at l)<)ll(nii hy Ili<' low i-idges of lli«* siiiallc
nerves.
EpiderDiis: Ventral willi cells much smallrr and riiinn<'r-wallc<i
than on the dorsal surface; stoniala on <'ach side of the bottom of
tlie furrows, somewhat ijrominent; many of the epidermal cells
extended into short, rather thin-walled, erect, unicellular i)ai)illae
with broad, rounded or truncate summits, and, especially at tlio
summit of the ridges, into longer, sharp-pointed, thick-wuUed, erect,
piickle-like hairs; typical bnlliform cells nom,', 1 nit at the bottom of
each furrow a gronp of nsually 3 large epidermis cells, which are
probably functionally homologous. Dorsal with tliic'k, porous walls,
which, in the rows containing stoniata, are unevenl}^ thickened so as
to appear wavy, 1 or more often 2 short cells alternating with the
longer ones; cuticle thick; stomata in very shallow furrows; hairs
and pai^illae none.
Suhepidernial stereome not as strongly developed as in most of the
strand grasses, in small grou^Ds on the dorsal side of each nerve; in
flattened sufjporting strands at the summit of each ventral rib and
extending some distance down its sides; and in comparatively small
strands in the leaf margins.
Chlorophyll chiefly in the j)arenchyma sheath of the mestonn^ Inin-
dles, Avith a "bridge" of small-celled chlorenchyina connecting each
two neighboring sheaths; palisade none.
Colorless parencliyma filling the ventral ribs abov<^ the mestome
bundles where it interrupts the ijarenchyma sheath, a few cells also
interrui^ting the parenchyma sheath on the dorsal side.
Mestome bundles surrounded l)y a mestome sheath whose walls
(esi)ecially the inner) are much thickened only on the leptonui side
of the larger nerves; parenchyma sheath (enveloping tlie mestome
sheath) containing chlorophjdl, continuous about the smaller nerves,
interrupted by colorless i^arenchyma above and l)elow the larger ones;
mestome i)arenchyina (thick- walled) in a single layer between the lep-
tome and the hadrome of the larger bundles.
Spartina stricta (Ait.) Koth.'
Leaf conduplicate when dry, not furrowed on the dorsal surface,
deei)ly furrowed on the ventral side, the funows aciii*-, I lie inter-
vening ridges broad and truncate at summit.
Epidermis: Ventral with cells nari'owci- and not s<> liigli as on
the dorsal surface, the walls as in .S'. jxdcns^ except that the outer
wall of each cell is covered with silicilied papillae; stomata on eacli
side of tlu^ bottom of the furrows; hairs none; typical bulliform <'ells
none, but 1 to 3 epidermal cells at bottom of each Ncntral furrow
somewhat larger than the others and probably functioning as bulli-
' Although this species belon-^'s to the salt marsh, it is described liere for the
sake of convenient comparison with theoth rGram neae. Compare Duval-.Touve,
Histotaxie, pi. .18, jig. r>. The Ocr icoke plant is nearly o£ the typical form.
2965 3
290
THE PLANT COVERING OF OCRACOKE ISLAND.
form cells. Dorsal as in S. patens, the short cells iisuall}' single,
here and there rounded, with strongly thickened walls, almost form-
ing papillae; stomata none; hairs none.
Hypoclermial colorless parenchyma in a single la^^er beneath the
dorsal epidermis,^ interrupted hy subepidermal stereome.
Stereome not strongly developed, a small subepidermal group on
the dorsal side of each mestome bundle; flattened supporting strands
(1 or 2 la^^ers) at the summit of each ventral ridge, not decurrent
along its sides; also in the leaf margins.
ChloreiicJiyma consisting of small palisade cells in a single laj^er,
radially arranged on each side of each mestome bundle and extend-
ing immediately beneath the epidermis to the stereome at the summit
of each ventral ridge ; each 2 neighboring laA^ers of palisade, between
each two nerves, either adjoining or separated by a few, large, color-
less iDarenchyma cells; chlorophyll also in most of the cells of the
parenchyma sheath.
Mestome bundles with mestome sheath and mestome parenchyma
much as in S. p)atens. Parenchyma sheath (around the mestome
sheath) of large cells, those adjoining the palisade laj^er containing
chloroi)hyll, the sheath occasionally interrupted on the dorsal side of
the bundle by a few
cells of the subepider-
mal stereome. Large
parenchj^ma cells, in 2
or 3 laj^ers, occup3dng
the thickness of the
ventral ridges and ap-
pearing to be an exten-
sion of the paren-
chyma sheath; when
in 3 layers, the middle
one colorless.^
YiQ.^l.—Chloris 2^etraea—\ea,f. blade. Transverse section. show-
ing the midrib in the keel, covered by layers of colorless tis-
sue and a group of buUiform cells (BC) on the ventral sur-
face; be, a small group of bulliform cells between two mestome
bundles. The mestome bundles are indicated by their paren-
chyma sheaths and by the stereome, which forms small sub-
epidermal groups. The thick walled mestome sheath is drawn
only in the two large bundles. Scale 84.
Chlorispetraea Sw.^
Leaf (fig. 37) becom-
ing conduplicate AAiien
^The specimen figured by Duval-Jouve. loc.cit., ha.s 3 or 3 layers.
'-Spartina stricfa mariiima (Walt.) Scribn., the common form elsewhere along
our Atlantic coast, is prat^tically identical in leaf anatomy with S. strictd from
Ocracoke, except in the following particulars: The epidermis cell walls on the
dorsal surface are thinner and less porous and show less of the wavy thicken-
ing: the short cells are more often in pairs, and, when single, are more often
papilliform; stereome is somewhat more strongly developed, as would be expected
from the larger size of the plant and the greater length of the leaves. The mate-
rial examined was from Lynnhaven Bay, Virginia.
'Figured by Duval-Jouve, Histotaxie, p. 35o, pi. IS, f. 1. For an example of
similar leaf structure compare the same nuthor's paper. "Etude histotaxifjue des
Cyperus de France," Mem. de I'Acad. de Montpellier, tome 1 pL 22, f. 6. 1874,
ANATOMY OF CHLORIS PETKAEA.
291
us
md slii(litly inii)ivssed veii-
mestome bundle nt tho aj)ox
keel. Hairs none.
hiilliforin cells in a iaih(M'
-5"*..
Fig. d8.—Chlnris])etruea— ventral portion of leaf blade.
Transverse section, showing epidermis (£/>) and
subepidermal stereome (St); at M the me.stome
sheath of a bundle, bordering on layers of colorless
parenchyma. Scale 240.
dry, strongly keeled on tiie dorsal face
trally opposite the niidvein, with a large
of and 3 smaller ones on each side of th(
Epidermis: Ventral, differentiated
wide band above the keel and
in 2 small groups of al)Out 4
cells each, 1 between the first
pair of nerves on each side of
the keel; elsewhere plurieellu-
lar (3 or 4 layers) and occu-
pying more than one-half of
the thickness of the leaf, ex-
cept above the larger nerves,
thin-walled (excei^t the outer
wall of the outermost layer)
and large (except the single
outermost la3^er where it lies
above the subepidermal groups of stereome) ; stomata none. Dorsal
epidermis one-layered, with cells all small, the outer wall and cuticle
much thickened, radial walls thin, undulate, one row of short cells
with strongly silicified walls alternating with several rows of long ones,
many of the cells developed into rounded, not silicified, papillae;
stomata in the strips of epi-
dermis which lie between
the nerves, level with the
epidermal surface.
Subepidermal stereome
(fig. 38) in flattened sup-
ports above and 1)elow the
mestome bundles, that on
the ventral side in 1 or 2
layers above the lai-ger
nerves, reduced to small
groups (sometimes only 2
cells) above the smaller
ones; on the dorsal side
supports stronger, some-
times 3-layered; also in
the leaf margins.
Chlorencli y /// a , pa 1 i sade,
arranged radially in a sin-
gle row of cells on each
side of each mestome l)undle, with a "l)ri(lge" of small-celle<l ehlo-
renchyma, containing usually a few cells of colorless parenchyma,
connecting each 2 neighboring i-ows; chlor<)])hylI likewise in Hie
parenchyma sheath where it adjoins the palisade.
Fig. 39.— CIdoris j^etraea— large mestome bundle from leaf
blade. St, stereome of lower face of blade, bordering on
the mestome sheath (M), which encircles both tlie lep-
tome and hadrome as a closed sheath of thick-walled,
porous cells. Bordering on the mestome sheath is a
green parenchyma sheath (P). VV, vessels; L, lacuno
with an annular vessel. Scale 560.
292
THE PLANT COVERING OF OCRACOKE ISLAND.
Mestome bundles each inclosed by a mestome sheath (figs. 38, 39, 40)
which has small cells with equally thickened walls; parenchyma
sheath with large, thin-walled cells containing chlorophyll where they
adjoin the palisade; mestome parenchyma in a single layer sepa-
rating the hadrome from the leptome of the larger bundles; com-
panion cells of the sieve tubes with much thickened walls.
..P
Fig. 40.—C'hloris j^etraea— three small mestome bundles from the blade. (Letters as in fig. 39.)
In a the mestome sheath is thick- walled only on the leptome side; in 6 and c the thickening of
the mestome sheath is more distinct and begins to show also on the hadrome side. The sheath
is closed in all of these small bundles and is a true mestome sheath. Scale 560.
Uniola paniculata L.^
Leaf rather thick and hard, more or less involute when dry, deeply
furrowed on the ventral surface, the intervening ridges broad and
truncate or but slightly rounded at summit; dorsal surface with very
slight corresponding depressions.
Epidermis: Ventral with cells smaller and thinner-walled than on
the dorsal surface, the outer w^alls more arched, many of the cells, espe-
cially on the sides of the furrows, extended into short, stout, pointed,
unicellular, antrorse, prickle-like hairs with cuticle rough and exces-
sively thickened (lumen almost obliterated except toward the base) ;
stomata near the bottom of the ventral furrows; bulliform cells in very
small groups at the bottom of the furrows. Dorsal with conspicuously
pitted walls and ver^^ thick,^ strongl}^ wrinkled cuticle, 1 or sometimes
2 or 3 short cells alternating in the same rows with long ones ; hairs
none; stomata less numerous than on ventral surface.
Stereome strongly developed (more so than in any other of these
strand grasses) ; strong, flattened subepidermal supports at the sum-
mits of the ventral ridges, separated from the mestome bundles by
thin-walled colorless parenchyma which also contains small, isolated
groups of stereome; narrow, mostly 2-layered subepidermal groups
on the dorsal side opposite the ventral furrows; strong subepidermal
supports on the dorsal side of each mestome bundle; finallj^, strong
marginal groups.
Chlorenchyma: Palisade small-celled, radially disposed on each side
of each mestome bundle in single layers, which are perpendicular to
' Compare Holm, Bot. Gaz. vol. 16, p/. 32, ff. 8 to 12, 1891.
2 But much less so than in Holm's material from Fort Monroe, Va,
ANATOMY OF YUCCA.
293
the leaf surface and extend nearly to the suniniit of the ventral ridges;
inside the layer of j)alisade, and parallel to it, is a single layer of large,
thin-walled parenchyma cells containing chloroph}'!!, which represents
an inii^erfect i^arenchyma sheath to the mestonie ])undles.
Colorless parenchyma in several layers which lie below the xmii-al
furrows and separate each two neighboring layers of palisado.
Mestome bundles without a true niestome sheath, but willi Urn lep-
tome sui-rounded by an unbroken ring of mes-
tome parenchyma having small cells with thick
porous walls.
Yucca aloifolia L.
Leaf isolateral, thick, especially toward the
base, ending in a rigid apical spine.
Epidermis (figs. 41, 42) ceils containing chlo-
rophyll, mostly somewhat elongated parallel to
tlie leaf axis, their walls, especially the arched
outer ones, greatly thickened and, together with
the miassive cuticle, exceeding the celllumen, the
radial walls not undulate; cuticle sharpl}^ differ-
entiated, beautifully stratified, divided b}^ per-
pendicular lamellsB corresponding to the radial cell walls; stomata
deeply sunken, lying beneath the cuticle at the bottom of urn-shaped
passages whose outer orifice is quadrangular with raised, cushion-like
borders, the ridges of exit at bottom of the pore very acute; papillae
none (perhaps present in younger leaves).
Interior of the leaf occupied by homogeneous, thin- walled paren-
chyma, which, toward the apex of the leaf, contains chlorophyll in
its entire thickness.
Mestome bundles lying in several rows in the mesophjdl, each sur-
rounded by a parenchyma sheath.
Stereome in massive groups on both tlie lep-
tome and the hadrome side of the bundles, espe-
cially strong on the hadrome side. Small bun-
dles of stereome, each with a parenchyma sheath,
are scattered among the mestome bundles.
Yucca gloriosa L.
Fig. U.— Yucca aloifolia —
leaf surface. Epidermis,
showing openings lead-
ing to the stomata. Scale
320.
Fig. i2.— Yucca aloifolia-
a stoma. Cross- section
Scale 320.
Leaf much like the preceding.
Epidermis with larger (higher) cells; dorsal
surface bearing thick, rounded, 1-celled papilhe.
Apical spine with exceedingly thick outer epidermis walls and
cuticle, these much higher than the celllumen, radial and inner walls
also much thickened; next a hypodermal layer of thick-walled col-
lenchyma; then 1 or 2 layers of thick-walled collencliy mafic tissue;
and, finally, a dense mass of stereome, inclosing a small central
mestome bundle.
294 THE PLANT COVERING OF OCRACOKE ISLAND.
Myrica carolinensis Mill.^
Leaf bifacial, thickisli, botli surfaces sprinkled with resiniferous
glands, appearing to the unaided eye as granules of resin.
Epidermis: Ventral, cells small, radial walls not undulate ; cuticle
thick, smooth; stomata none; long, pointed, unicellular hairs with
thick- walled, smooth cuticle scattered along the veins; short-stalked,
suj^erficially flat, scale-like, pluricellular glands occupying deep
depressions but usually rising above the level of the epidermis, these
filled with a mass of bright-yellow resin which breaks down the cell
walls and finally itself disorganizes, the stalk of each gland radially
surrounded by numerous small foot cells. Dorsal similar, but cuticle
less thickened, glands less numerous, and stomata present, lying in
all directions, each surrounded by 5 to 7 ordinary epidermis cells, the
guard cells slightly prominent.
Chlorencliyma sharply differentiated into one very compact layer
of i)alisade with high, narrow cells, and several layers of open pneu-
matic tissue with rather large intercellular spaces.
Colorless thin-walled parenchyma in narrow plates interrupting the
chlorenchyma above and below the smaller vein^.
Hypodermal collenchymatic tissue, thick-walled, in 2 or 3 layers
above and below the midvein.
Mestome bundles of midvein reinforced by stereome which adjoins
both the hadrome and the leptome, that below the leptome separated
from the hypodermal collenchymatic tissue by a little thin-walled
parenchyma.
Myrica cerifera L.
Leaf usuall}^ somewhat thinner than in M. carolinensis.
Epidermis similar, but with fewer hairs along the veins.
Palisade somewhat thicker, in 2 layers of lower cells.
QUERCUS VIRGINIANA L.^
Leaf persistent, thick, bifacial, upper surface shining, margins
sometimes revolute, veins, especially the midvein, prominent beneath.
Epidermis: Ventral with nonundulate cell walls, the outer, espe-
cially, strongly thickened ; cuticle thick, smooth; stomata none; hairs
none. Dorsal, cell walls as on the ventral surface ; stomata with guard
cells slightly i)rominent, lying in all directions, each bordered by sev-
eral small epidermis cells; hairs (fig. 43) forming a dense covering,
stellate, consisting of 8 to 18 acute, thick-walled unicellular arms
upon very narrow foot cells, cohering toward their bases so as to form
a saucer-shaped scale.
^ Material examined from near Norfolk, Va.
^Q. virens Ait. Material examined was from near Norfolk, Va. Compare
Quercus ilex as described and figured by Lalanne, Recherches, p. 3, pL 7, ff. 9, ii.
ANATOMY OF ZANTHOXYLUM CLAVA-HERCULIS. 295
Hyp(xlena mostly :3-hiyered, colleneliyniatie, continuous on \hA\\
surfaces (rarely interrupted hy palisade), replacing the chloren-
chyma and forming thick masses above and especially below the
mid vein.
Sfereome thin-walled, in narrow plates interrupting the chloi-cn-
chyma and extending through the leaf opposite most of thr smaller
veins; in strong masses above and below the midvein.
Chlorenchyma: Palisade compact, mostly in 2 layers, passing grad-
ually into pneumatic tissue of which only the low-
est layer is comparatively open and short-celled.^
ZANTHOXYLUM CLAVA-HERCULIS L.-
Leaf bifacial, thickish, dark green and shining
above.
Epidermis: Ventral, cells large, walls not undu-
late, the outer strongly thickened, the others thin;
cuticle sharply defined, delicately wrinkled; sto-
mata none ; hairs none. Dorsal, cells smaller, the
outer walls and cuticle thinner ; stomata with guard a/ia-steiiate hair from
cells slightly prominent, lying in all directions, dorsal leaf surface.
surrounded by 4 to 6 epidermis cells; hairs none, scale m ^^^
HypodeTmal coUenchyma with strongly thick-
ened walls in 4 or 5 narrow laj^ers above the midvein ; coUenchymatic
tissue in 4 or 5 wide layers beneath the midvein.
Chlorenchyma: Palisade a single compact layer of short cells;
pneumatic tissue in 2 or 3 layers, rather open.
Oil reservoirs schizolysigenous,^ scattered through the mesophyll
near the ventral surface, and larger ones at the base of each indenta-
tion of the leaf margin, surrounded by 2 or 3 layers of thickish- walled
parenchyma with cells strongly compressed parallel to the surface of
the cavity.
Mestonie bundles surrounded by a thin, interrupted sheath of stere-
ome, which is continuous and (in cross section) crescent-shaped out-
side the leptome.
' Quercus laurifolia Michx. is a deciduous-leaved species, common along the
coast and ijerhaps occurring upon Ocracoke Island. Leaves from Cape Henry,
Va., show the following differences from Q. virginiana:
Epidermis: Cuticle thicker; dorsal surface less densely covered with similar
stellate hairs, their arms longer, more slender and much thinner- walled.
Collencliymaticliypoderm none except above the midvein. True coUenchyma
(hypodermal) strongly developed beneath the midvein.
Stereome entirely surrounding the midvein, ^vllere it is much thicker-walled
than in virginiana.
Chlorenchyma: Only the uppermost layer typical pahsade; pneumatic tissue
more compact and with more elongated cells than in civgtniana,
-Material from Virginia and Mississippi.
=* Compare Solereder, Syst. Anat., p. '201.
2^6
THE PLANT COVERING OF OCRACOKE ISLAND.
Croton maritimus Walt.
Leaf flat, bifacial, both surfaces densely covered with a gray, scale-
like pubescence.
Epidermis: Ventral, cells small, walls not undulate, thin; siomata
vei-y numerous, guard cells level with the epidermis, each stoma sur-
rounded b}^ 4 epidermal cells,
of which 2 are differentiated
as crescent-shaped subsidiary-
cells parallel with the guard
cells; hairs pluricellular, stel-
late, consisting of a long cylin-
drical stalk rising above the
surface and composed of many
smaU cells partlj^ of subepi-
dermal origin, from the apical
cell of Avhich radiate in a
nearly horizontal plane nu-
merous unicellular, sharp-
pointed arms with thick,
smooth cuticle, cohering near
their bases so as to form a shal-
low cup. Dorsal, similar ; cu-
ticle thickened and granular
Fig. 44. — Cro/o?i maritimus— Yisiiv from dorsal leaf
surface, o. View from above; &, cross section; Ep,
epidermis; P, palisade. Scale 340.
underneath the large veins;
stomata about equally numerous; hairs (fig. 44) with less numerous
and thinner-walled arms.
Hypoderin^ none, except beneath the large veins, where several
layers of thin- walled collenchymatic tissue occur.
Stereome, none.
Chlorenchyma: Palisade in one layer, comi3act, the cells elongated,
interruiDted onh^ by thick-walled, branching, sclerotic idioblasts;
pneumatic tissue of roundish cells. •*
Ilex vomitoria Ait.
Leaf evergreen, thick, shining and dark green above, bifacial.
Epidermis: Ventral, cells rather high (but small in their diameter
parallel to the leaf -surf ace), the outer wall and cuticle much thick-
ened but not nearly so high as the cell lumen, radial walls rather
thin, undulate; cuticle smooth; stomata none; erect, short, stout,
pointed, often curved, prickle-like unicellular hairs with ver^^ thick
walls (lumen almost obliterated) and smooth cuticle along the mid-
vein.* Dorsal, cells smaller, thicker- walled (outer wall and cuticle
exceeding the cell lumen in height), the radial walls nearly straight,
porous; cuticle Avrinkled; stomata very numerous, guard cells slightly
depressed; hairs, none.
' This specie*! is, therefore, an exception to the rule that evergreen leaves have
no hairs on the upper or ventral surface. (See Lalanne, p. 117.)
ANATOMY OF TEUCRIUM NASHII. 297
Hijpoderinal collenchymatic tissue in a single ntirrow Uiyer abov«
the luidvein (as in I. opaca) and several layers beneath the raid vein.
Chlorenchyma: Palisade in two layers; pneumatic tissue rather
open (more so than in I. aquifolium and I. opaca).
Mestome bundle of midvein reinforced by a narrow group of stereom.
below the leptome, and a thinner- walled gronp above the hadromeJ
Oenothera humifusa Nutt.
Leaf densely silky-pubescent, imperfectly bifacial, midvein slight l.\
impressed above, not prominent beneath.
Epidermis similar on both surfaces, cell walls not undulate, som<'-
what thickened, especially the outer; cuticle smooth; stomata witli
guard cells level with the upper surface, slightly prominent beneath,
the majority lying parallel to the veins, but many irregular; hairs
densely matted, subappressed, long, sharp-pointed, unicellular, with
thick, granular cuticle, each radially surrounded by 5 or 6 foot cells.
Hypodermal collenchyma in 2 narrow layers above and 1 wide
layer beneath the midvein, separated from the mestome above and
below by colorless (water-storage?) parenchyma.
Stereome, none.
Chlorenchyma not sharply differentiated; palisade containing large
cells inclosing raphides, which are yet more abundant in the other-
wise rather compact pneumatic tissue.
Teucrium NASHII Kearney. ^
Leaf normally horizontal, bifacial, dark green above, white-tomen-
tous beneath, margins (especially in young leaves) somewhat revolute,
veins impressed above, prominent and reticulated beneath.
Epidermis: Ventral, cell walls thin, the lateral not undulate or but
very slightly so; cuticle smooth; stomata, none; hairs scattered,
mostly 3 or 4 celled, thin-walled, smooth, slender, very sharp-pointed,
strongly bent so as to lie nearly parallel to the surface, surrounded
radially by 4 to 10 (most frequently 6) foot cells. Dorsal, cell walls
more undulate; stomata in the sheltered interstices between the pro-
jecting veins, with guard cells slightly prominent, lying in all direc-
tions, usually bordered by 2 epidermal cells and at right angles to
their dividing wall, but with many exceptions; long-pointed hairs
forming a dense covering; also very numerous, spherical, sessile, glan-
dular hairs Avith roughened cuticle.
Hypodermal collenchymatic tissue in 2 or 3 narrow layers above and
'Specimens cultivatedTat Washington, D. C, differ in having :3 layers of pali-
sade, and no stereome above the hadrome of the midvein.
•'Teucrium cauadensc, which is never, to my knowledge, a strand plant, differs
ohieflv in the less dense hairy covering of the dorsal leaf surface and in the dis-
tinct granular roughening of the cuticle in the pointed, as well as the glandular
hairs.
298
THE PLANT COVERING OF OCRACOKE ISLAND.
1 wide layer beneatli the midvein, the latter separated from the lex)-
tome b}^ several layers of colorless parenchjnna.
Stereome, none.
Chlorenchyma: Palisade a single laj^er of short cells, very compact;
pneumatic tissue occupying the
rest of the leaf's thickness, also
rather compact.
Physalis viscosa L.
Leaf flat, thin, imperfectly bifa-
cial, gray-canescent or green (de-
pending upon the amount of
pubescence).^
Epidermis similar on both faces,
cell walls not thick, the radial un-
dulate ; cuticle above and beneath
the veins thick and warty; stomata
much more numerous on the dorsal
surface; hairs (fig. 45) about
equally numerous on both faces,
Fig. i5.— Physalis viscosa— branched hair from thiu-walled with granular CUticle,
leaf. Scale 240. cousisting of a uuicellular stalk
bearing 3 or 4 (usually 3) conical, acute, unicellular or sometimes
bicellular arms, these in turn sometimes once-branched.
Hypodermal colleiichy matte tissue above and beneath the veins.
Stereome^ none.
Chlorenchyma: Palisade and pneumatic tissue not well differen-
tiated, both compact.
^ The individuals observed upon Ocracoke Islaad had greener, less pubesceut
leaves than at Cape Henry, Va.
ANATOMICAL SUMMARY OF SAND-STRAND SPECIES.
299
Leaf anatomy of sand-strand species.
[The sign x indicates presenct of character : ± its imperfect development.]
Leaf.
Epidermis.
Cuticle
(3
h
II
3
1
i
Species.
■3
1
"2
1
1
V
>
i
a
i
0,
H
o
1
Pauicum amarum
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
x
X
X
Muhlenbergia tilipes
Spartina patens
Spartina stricta^
X
Chloris petraea
X
X
Uniola paniculata
X
X
X
X
Yucca aloif olia
X
X
Yucca gloriosa
Myrica carolinensis
X
X
X
X
X
X
X
X
X
My rica cerif era
Quercus virginiana
X
X
Zanthoxylum clava-herculis
X
Croton maritimus
±
Ilex vomitoria
X
X
X
X
Oenothera humif usa
Teucrium nashii
±
X
Physalis viscosa
X
Epide
rmis.
Stomata.
Species.
i
OQ
1
>
1
"a
1
a
a
s.
I
a
t
a
1
si
I
i
n
.11
Panicum amarum
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Muhlenbergia filipes
Spartina patens
Spartina stricta
X
Chloris petraea
X
X
Uniola paniculata
X
X
X
X
Yucca aloifolia
X
X
Yucca gloriosa
X
X
X
Myrica carolinensis
X
X
X
X
X
X
X
X
Myrica cerifera.
Quercus virginiana..
Zanthoxylum clava-herculis
Croton maritimus
X
X
Ilex vomitoria
X
X
Oenothera humifusa
X
X
X
X
X
Teucrium nashii
X
X
Physalis viscosa
X
1
1
1 Belongs to the Salt Marsh, but is inserted here for convenience of comparison with other
Gramiueae.
300
THE PLANT COVERING OF OCRACOKE ISLAND.
Leaf anatomy of sand-strand species — Continued.
Epidermis.
Hypoder-
mal colleu-
chyma or
collencby-
matic tissue.
Hairs.
Species.
r
in
1-
1
3
6
a
1
1
1
111
II
2
1
T*nnir>mTi amaTiTm
Mulilenbergia filipes . . .
X
X
X
X
X
X
OViloritj ■nptrflPfl
X
X
X
Viirr-n nlnifnlia
1
Myrica carolinensis
Myrica cerifera
X
X
X
X
X
X
X
X
X
^(
X
X
X
X
X
X
X
Zanthoxylum clava-
herculis
X
X
X
X
X
X
X
X
X
X
X
X
TIptt vnmitoria
X
X
X
X
X
X
X
X
X
Tf^nnvinm TintiViii
X
Physalis viscosa
X
Stereome.
Chlorenchyma.
Water par-
enchyma.
Mestome
bundles.
Species.
1
1
1
i
1
a
q-l
1
a
o
tn
a^
^§
.a-Q
:o
<
§
Oi
a
1
1
s
f
il
ii
Is
il
r
il
ill
111
IP
III
1
.a=^
a .
®|
Q
i
2
0)
1
g
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Muhlenbergia fllipes . . .
Spartina patens
Spartina stricta
Chloris petraea .
Uniola paniculata
Yucca aloif olia
X
X
X
X
X
X
X
_
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Mvrica carolinensis
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Zanthoxylum clava-
herculis
Ilex vomitoria
X
X
Teucrium nashii
X
V
+ ! V
ANATOMY OF TRIGLOCHIN AND JUNCUS. 301
SALT MARSH SPECIES.
TRIGLOCHIN STRIATA Ruiz tfc PaV.
iea/ isolaterul, thickish.
Epidermis cells with noimndulMte walls, the? outer strongly lliick-
ened; cuticle thick, granular; stoniata in rows parallel to the nerves,
level with the surface, each bordered by 4 epidermal cells, of which 2
are subsidiary and resemble the guard cells; hairs ncjiie.
Stereome none.
Chlorenchyma: Two outer layers compact, continftous on l)oth sur-
faces, not imlisadic excei)t at the leaf margins, where o layers of i)ali-
sade occnr; parenchyma of the interior of the leaf containing little
chlorophyll, interrnpted by lacunes.
Mestome hundles imbedded in the interioi- x^arenchyma, each sur-
rounded by a small-celled mestome sheath, whose inner walls are
excessively thickened and layered ; this surrounded by a sheath of
large-celled, colorless parenchj^ma.
Spartina stricta (Ait.) Roth.
Treated for comparison among sand-strand grasses, page 289.
JuNCUS ROEMERIANUS Scheele.
J/er// vertical, terete, sharp-pointed, stem-like.
Epidermis cells all small, quadrangular (superficially), regular,
without alternation of long and short cells; smaller and thicker- walled
over the bands of chlorenchyma than over those of subepidermal
stereome, the outer walls much thickened and porous; stomata^ with
guard cells level with the oilier epidermal cells; hairs none.
Stereome (subepidermal) alternating with the chlorenchyma in
strong groups, which in cross section are I-shaped.'^
Cldorencliyma of typical long, narrow palisade cells, mostl}" in 5 or
6 layers.
Mestome hundles arranged in several concentric circles, com-
pletely surrounded hy stereome (which is particularly strong on thc^
two sides parallel to the leaf surface), the whole enveloi^ed by a
beautifully i-egular, large-celled parenchyma sheath. Within the
stereome the bundle is encircled by a mestome sheath of small, thick
walled* cells. The outer mestome bundles, with the colorless pareii-
ch3"ma between, form a continuous ring, unbroken by lacunes. The
inner bundles lie in tliin longitudinal plates of parenchyma, wliich
separate large lacunes. Small bundles of stereome, each surrounded
by a i)arencli3nna sheath, also occur in tlie interior of the leaf.
Stem differing but little from the leaf; difference consisting cliiefly
in the presence of a cortex of some thickness, and in llie less elon-
gated chlorenchyma cells.
'Of the type common in Jnncaceae, Cyperaceae, and Gramineae.
2 '* I-formige Trager "' of fecliweudener.
302 THE PLANT COVERING OF OCRACOKE ISLAND.
Sesuvium maritimum (Walt.) B.S.P.^
Z/ea/ isolateral, somewhat succulent.
Epidermis cells with non undulate, radial walls, the outer some-
what thickened, some of the cells much larger and probably serving
for water storage; cuticle smooth; stomata Ij^ing in all directions,
guard cells level with the epidermis, each stoma bordered by 3 to 0
(usually 4 or 5) undifferentiated epidermis cells; hairs none.
Stereome none.
Chlorenchyma homogeneous and occupying the entire thickness of
the leaf, interrupted by large intercellular spaces, which lie beneath
the large (water- storage) epidermal cells.
Mestome bundles with a small group of collenchyma on the leptome
side.
Stein: Epidermis with cell walls, especially the outer, strongly
thickened. Stereome none. Collenchyma in small groups above the
leptome of the primary mestome bundles. Cells containing crystal
masses in the pith and a few in the cortex.
TissA MARINA (L.) Britton.^
Leaf isolateral, hemicylindric, furrowed, margins sparsely ciliate,
especially toward base.
Epidermis with cells somewhat elongated parallel to the leaf axis,
the radial walls strongly undulate, the outer walls
slightly thickened; stomata always parallel to the
leaf axis, guard cells slightly prominent, lying usu-
ally between 2 ordinary epidermis cells and at right
angles to their dividing wall, but sometimes bordered
b}^ 3 cells; hairs (on the margins) glandular (fig. 46),
capitate, with a 3 or 4 celled stalk.
FIG. m.-Tissa mar- Stereome none.
^■na— glandular hair CMorenchyma compact, its cells not elongated.
Scale 240^ margin. Colovless parenchyma (water tissue) constituting
the interior mesophyll.
MesUyme bundle of the midvein small, lying deep in the water tissue,
with a small group of collench3ana outside the leptome.
Stem: Epidermis with thick outer cell walls and wrinkled cuticle.
Outer cortex separated from the inner by an unbroken, 2-la3^ered ring
of stereome, with cell walls (especially of the inner layer) compara-
tively thin.
^ Sesuvium pentandr} nil Ell. — Compare Warming's description and figure of
^. portulacastrum, Halofj^t Studier. pp. 180, 211.
■^ Spergularia salina J. and C. Presl.
ANATOMY OF VINCETOXICLM PALUSTRE. 303
KOSTELETZKYA VIRGINIC'A (L.) A. (4r{iy.
Ledfhi'Oixd and flat, bifacial, stellate-pubescent on l)(>th surfaces.
Ejjide/Diis cells with iioiiundulate, thin walls, except above and
beh)\v the larger veins, wliere the cuticle is rather thick and layered;
stomata witli guard cells sliglitly proiiiin(^nt, more numerous on tlie
dorsal surface; hairs stellate, consisting of 5 to 8 acute unicellular
arms with thick, smooth cuticle, separate nearly or quite to the l)ase,
each from a narrow foot cell in the epidermal plane.
Hypoderrtial colleiichyma strongly developed above and below the
larger veins.
Chlorerichyriia: Palisade 1-layered; pneumatic tissue with numer-
ous small intercellular spaces; mucilage cavities distribut(Ml in the
chlorenchyma.
Mestome bundles almost completely surrounded by a thin, inter-
rupted sheath of stereome, which is most strongly developed outside
the leptome.
Ammania koehnei Britton.
Leaf ^at, rather thin, aijproximately isolateral.
Epidermis: Cells with radial walls strongl}^ undulate ; all the walls
thin, except above and below the larger veins, where the outer walls
are considerably thickened; cuticle smooth; hairs none; stomata
chiefly parallel with the veins, but some irregular; guard cells slightly
prominent, each stoma bordered by usually 4 undifferentiated epi-
dermal cells.
Collencliyma none.
Stereome none.
Chlorenchyma homogeneous, not imlisadic.
ViNCETOXicUM PALUSTRE (Pursh) .\. Gray.^
Leaves narrow, sharply reflexed and hanging almost vertically,
imperfectly isolateral.
Epidermis: Cell walls rather thick, not undulate; cuticle wrinkled,
especially above and below the veins; stomata more numerous on the
ventral surface, level with the epidermis, each bordered by 4 or (more
often) 5 ordinary epidermis cells, generally parallel with the leaf
axis on the ventral surface, very irregularly disposed, often at right
angles to the axis on the dorsal surface; hairs none.
Hypoderni a single, narrow layer, only above the midrib.
Collenchyma none.
Stereome none.
Chlorenchyma not palisadic, homogeneous through IIh' l«'af. bnl
the interior containing less chlorophyll.
Cells contain iiKj masses of crystals (calcium oxalate) scattcicd in
the chlorenchj^ma.
Stem: Epidermis as in the leaf.
' Seutera inaritima Decsne.
304
THE PLANT COVERING OF OCRACOKE ISLAND.
Hypoderm continuous, 1-Ui3'ered. Outer cortex with rather thick-
walled cells, containing chlorophyll; inner cortex gradually becoming
thinner- walled and colorless.
Stereome in a concentric band of isolated groups, lying Inside the
middle of the cortex.
Lactiferous ducts few, Ijang just outside the mestome bundles.
Mestows hundles bicoUateral,
perileptomatic, the leptome most
strongly developed on the outer
l^eriphery of the hadrome.
LiPPIA NODIFLORA Mx.
Leaf^ imperfectly bifacial, usu-
ally horizontal, but sometimes
vertical.
Epidermis alike on both sur-
faces, cell walls thick, not undu-
late; cuticle wrinkled; stomata
(fig. 47) lying in all directions,
guard cells almost level with the
ventral surface, slightly depressed
on the dorsal surface, each stoma
bordered by 2 crescent-shaped,
chlorophyll - holding, subsidiary
cells which are usually at right
angles to but often nearly or quite
parallel to the guard cells, and of
which one is usuallj^ considerably
larger than the other; hairs abun-
dant on both faces, iDarallel to the
veins, appressed, lying in slight
grooves of the epidermis, each attached b}^ its middle (hence 2-armed)
to a short cylindrical foot cell, which is bordered by several wedge-
shaped (as seen from above) radiallj^ arranged epidermis cells, the
free cell with a very thick, warty cuticle.
Hypodermal collenchynla (not very typical), in 1 or 2 layers above
and 3 or 4 below the principal veins, intermitting the chlorenchyma
in full-grown leaves.
Chlorencliyma: Palisade 2-layered, the cells rather short; pneu-
matic tissue rather compact, not well differentiated from the palisade,
but its cells more nearly isodiametric and containing less chlorophyll.
Mestome hundles (of larger veins), with some stereome below the
leptome and a small group of collenchj^ma above the hadrome, which
finall}^ becomes continuous with the subepidermal group of col-
lenchj^ma.
Fig. 47.—Li2ypia nodiflora— stomata and hairs,
a, Stomata on leaf; t», hair and stoma on ventral
leaf surface; c, hair on dorsal surface. Scale
240.
' Compare Warming. Halofyt-Studier, p. 3oo, and Solereder, Syst. Anat.,p. 713,
ANATOMY OF MONNIERA AND SOLIDAGO. 305
MONNIERA MONNIERA (L.) BRITTOX.'
Occurs in 2 forms; one in shallow pools, largely submersed, willi
long stems, elongatcnl internodes, and larger loaves; the other terres-
trial, in wet sand, with short, creeping stems, contracted internodes
and smaller leaves.
(a) Aquatic form. Structure that of a partially submersed hydro-
phyte, with thin- walled tissues, much reduced mestome system, no
mechanical tissue, etc.
Leaf isolateral.
Epidermis: Cells with undulate lateral walls, the walls thin except
the outer, which is somewhat thickened; cuticle delicately wrinkled;
stomata more numerous on the dorsal surface, guard cells about level
with the epidermis, bordered by 2 to 4 ordinary epidermal cells; hairs
none.
Chlorenchynia homogeneous, palisade none.
Mestome bundles immediately bordered by chlorenchyma, not rein-
forced by stereome or collenchyma.
Stem: Epidermis as in the leaf.
Cortical parenchyma in 1 or 2 continuous layers just beneath the
epidermis and. around the central cylinder, elsewhere in 1-layered
plates, separating the large lacunes.
Mestome cylinder composed of several bundles, inclosing a small
quantity of pith.
(6) Terrestrial form. The only tangible differences from the aquatic
form are: Stomata about equally numerous on both leaf surfaces;
mestome bundles somewhat more developed and walls of the vessels
more lignified; mesophyll somewhat more compact.
Solid AGO sempervirens L.^
Leaf somewhat fleshy, vertical or nearly so, apjjroximately isolat-
eral.
Epidermis: Cells with nonundulate radial walls, only the outer
strongly thickened, except above and below the larger veins; cuticle
strongly wrinkled; stomata numerous on both faces with guard cells
level with the surface, bordered by usually 4 ordinary epidermal cells;
hairs none.
Hypodermal collenchyma in only 1 or 2 narrow layers above and
3 or 4 wide layers below the larger veins.
CJdorenchyma homogeneous, none of it typical palisade, frequently
interrupted, especially opposite the mestome bundles, b}' plates of
colorless, thin- walled parenchyma (water tissue), which extend froni
the ventral to the dorsal epidermis, and ultimately break down into
large lacunes close beneath the epidermis.
^ Herpestis mouuiera H. B. K.
Th(
2965-
306 THE PLANT COVERING OF OCRACOKE ISLAND.
Ducts (probablj^ resiniferous) numerous, especially near the dorsal
surface, a^iparently always Ij^ing in the lilates of Avater tissue, one
below the leptome of the mid vein.
Mestome bundles of the larger veins with a narrow (in transA'erse
section crescent-shaped) group of comparatively thin- walled stereome
above the hadrome.^
Aster tenuifolius L.
Leaves narrow, almost vertical, isolateral, thick, with a deep groove
on the dorsal surface on each side of the midvein, margins slightly
incurved.
Epidermis: Cells comi)aratively large, walls not undulate, the outer
greatly thickened; cuticle wrinkled and with slight furrows corre-
sponding to the radial walls of the epidermal cells ; stomata rather
few and large, the guard cells slightly sunken, mostly somewhat
deflected in direction from that of the leaf axis, bordered by usually
3 ordinary epidermis cells; hairs none.
♦ Hypodermal collenchyma in a few narrow layers above and rather
wide layers below the midvein.
CMorenchyma consisting of palisade with high, narrow cells, in
about 2 layers on both faces, strongly converging toward the mid-
vein, especially on the ventral side.
Colorless parenchyma (water- storage tissue) occupying the interior
of the leaf in small quantity, and surrounding the midvein, where it
replaces the palisade.
Mestome bundles not reinforced by stereome.
Aster subulatus Michx.
Leaves wider and thinner than in the preceding, almost vertical,
isolateral, flat, impressed above the midvein, which below is i^romi-
nent, with a furroA^^ on each side of it.
Epidermis: Cell Avails not undulate, thick, the outer A^er}^ thick,
the inner collenchymatic-thickened A\^here hypodermal collenchyma
occurs; cuticle wrinkled; stomata, with guard cells lying parallel to
the leaf axis, level Avith the surface; hairs none.
Hypodermal collencliyma above and below the A^eins (about 4 laj^ers
betAveen the leptome of the midA^ein and the dorsal epidermis) and in
the marginal angles.
CMorenchyma, of compact palisade, occupying i^ractically the entire
thickness of the leaf except Avhere collenchyma occurs and about the
midA^ein.
'The leaves of nonmaritime species of Solidago (e. g., S. petiolaris, S. neglecta,
and S. erecta) exhibit some interesting differences from S. sempervirens. All three
have bifacial leaves with compact palisade and open pneumatic tissue (chloren-
chyma least differentiated in S. petiolaris). Stomata few {S. erecta, S. neglecta)
or none {S. petiolaris) on the ventral surface, guard cells slightly prominent on
the dorsal surface. Hairs along the veins, especially on the dorsal face in S. petio-
laris, 3 or 4 celled sharp-pointed, bent.
ANATOMY OF BACCHARIS HALIMIFOLIA. 307
Colorless parejicliynia (water-stonige tissue) above and on each side
of the mid vein.
Mestome bundles without stereome supports, but with a small irreg-
ular group of collenehynia lying outside the hadrome.^
BaCCHARIS HALIMIFOLIA L,
Leaves thickish, nearly vertical, isolateral.
Epidermis: Cell walls not undulate, thickened, the outer ones greatly
so; cuticle warty, especiall}^ on the dorsal surface; stomata mostly
parallel to the veins, but many somewhat deflected, guard cells slightly
prominent, each stoma radially bordered by 4 or o small epidermis
cells.
Colleyicliyma (hypodermal) replacing chlorenchyma above and below
the larger veins (0 or 7 layers below the leptome of the midvein),
containing no ducts. ^
Chlorenchyma: Palisade occupying the whole thickness of the leaf
between the veins, rather open, especiall}^ that in the interior of the leaf
(but typical pneumatic tissue none), converging toward the midvein
on the dorsal side; large, deep air chambers underneath the stomata.
Colorless parenchyma (water tissue) in 2 layers on each side of the
midvein (cells circular in cross section), in a single layer entirely sur-
rounding the smaller bundles.
' Three nonmaritime species of Aster were selected for comparison with the two
salt-marsh species: A. puniceuH, a broad-leaved plant of boggy ground, and .1.
dumosus and A. ericoides, narrow-leaved species of dry, sandy soil.
A. ericoides has a practically isolateral leaf, epidermis alike on both faces, with
undulate radial and thickened outer walls, finely wrinkled cuticle, guard cells of
the stomata level with the ventral surface, slightly prominent on the dorsal sur-
face; chlorenchyma near both surfaces compact and small-celled, more open and
larger-celled in the interior of the leaf; hypodermal collenchyma in '2 layers above
and below the midvein; water parenchyma none.
^4. dumosus has a distinctly bifacial leaf, epidermis much as in .1. ericoides, but
the 2 surfaces more differentiated, the ventral with radial cell walls less undulate
and outer walls less thickened than in ^4. ericoides, cells larger and stomata much
fewer on the ventral surface, the dorsal with radial walls more strongly undu-
late, and scattered, slender, pointed, few-celled hairs along the veins: ])alisade com-
pact, pneumatic tissue open: veins supported by hypodermal collenchymatic tissue.
A. puniceus shows, of course, the greatest amount of difference from the salt-
marsh forms. It has a flat, approximately horizontal, bifacial leaf. The ventral
surface is rough with thick- walled, prickle-like, 1-celled hairs, mixed ^vith scat-
tered, longer, more slender, and thinner-walled hairs: the stomata lie in all direc-
tions in and have their guard cells level with the dorsal surface, but are wanting
on the ventral face: the cuticle is smooth; the chlorenchyma is differentiate<l into
a single layer of compact palisade and a few layers of rather open pneumatic tis-
sue; no colorless parenchyma occurs inside the epidermis.
On the whole the salt-marsh Asters show less anatomical divergence from inland
forms than does the salt-marsh Solidago. Of the two species, .1. fenidfoliKs
exhibits a more distinctive halophytic, or rather xerophytic, structure than does
^4. suhulatiis.
-Warming, Halofyt-Studier, p. 195, describes ducts which occur in the collen-
chyma of the leaf of Baccharis dioica.
308
THE PLANT COVERING OF OCRACOKE ISLAND.
Mestoine bundles Avith a strong groui) of stereome on\y outside ihe
hadrome in young leaves, in older leaves a corresponding grouj) of
more numerous and smaller cells outside the leptome also.
IVA FRUTESCENS L.^
Leaf thick, usuall}^ almost vertical, nearly isolateral.
Epidermis cells small, walls not undulate, thick, especially the
outer; cuticle wrinkled, especially above
and below the veins; stomata small, about
equally numerous on both surfaces, the
guard cells sunken, especially on the dor-
sal surface, lying irregularly in all direc-
tions; hairs on both surfaces (fig. 48) ap-
pressed, antrorse, thick-walled, 2 or 3
celled, sharp-pointed, the terminal cell
abruptly narrowed just above its base,
each hair borne upon 5 or 6 radially
arranged foot cells which form a cushion
that projects above the level of the epider-
mis; glands, 2 or 3 celled, sessile, nearly
spherical, almost filling depressions in the
epidermis and rising slightly above its gen-
eral level.
Hypoderriial collenchyma in strong
groups above and below the larger veins
(about 10 layers above and below the mid vein).
Chlorenchyma palisadic, in several layers, the cells small and
narrow, those near the mid vein converging toward it; palisade fre-
quently interrupted (especiall}^ opposite the mestome bundles) by a
few rows of thin- walled, colorless parenchyma (water tissue), which
ultimately breaks down into lacunes. Large ducts, each surrounded
by a sheath of small cells, occur in the water tissue, esijeciall}^ on the
ventral side of the leaf.
Mestome bundles with a little thin-walled stereome over the
hadrome.^
Fig, 48.— Ira frutescens— hair from
ventral leaf surface. Scale 320.
^ The material examined was collected near Virginia Beach, Virginia.
- Iva imbrlcata Walt, is a common plant of the Atlantic sand strand in the
Southeastern States, although not observed upon Ocracoke Island. It presents
some interesting differences from the salt-marsh /. frufescens. The leaves exam-
ined were collected near Cape Henry, Virginia.
The plant is strongly arom itlc, the leaf perfectly isolateral, fleshy and smooth.
Epidennis: cells much larger: cuticle not wrinkled; s omata with guard cells
level with the ventral surface, somewhat sunken on the dorsal; hairs none.
Collenchuma less strongly developed than in /. frutescens.
Chlorenchyma consisting of 2 or 3 layers of palisade on both surfaces.
Colorless parenchyma (water-storage tissue), filling the interior of the leaf and
interrupting the palisade above and below all the veins.
Mestoine bundles lying in the midst of the water-storage tissue; stereome none.
The most important differences in /. inibricata are the strong development of
ANATOMY OF BORRICHIA FRUTESCENS.
309
BORRICHIA FRUTESCENS (L.) DC'.
Leaves (fig. 49) fleshy, jilniost vertical, imperfectly isolateral, the sur-
face glistening, whitish, mealy looking, especially in young leaves.
Epidermis (fig. 49) with small, thin- walled cells, very many of
which are extended by tangential division into commonly 2 to 4
celled, thin- walled, pointed, usually bent haii's (fig. 50),' the whole
forming a very dense covering and giving the leaf its peculiar, glis-
tening aspect; stomata only on the ventral surface, the guard cells
slightly sunken.
Collenchyma (hypodermal) in several layers abov(^ and l)elow the
large mestome bundles (five in the midvein).
CJdorenchyma consisting of very compact palisade, 2-layered on
.both surfaces; pneumatic tissue none.
Colorless parenchyma (water-storage tissue) (fig. 49) occupying the
FiqA9 .—Borrichia frutescens—\ea,{ section. Trans-
verse section, showing epidermis of ventral sur-
face (Ep); palisade (P); colorless parenchyma
(C T); hadrome (H) and leptome (L) of a small
mestome bundle; and epidermis of dorsal surface
(ep). Scale 320.
Pig. 50.— Borrichia
frutescens—leat-
hairs. Scale 340.
interior of the leaf and forming rather more than one-half its thick-
ness, at somewhat regular intervals displacing the i>alisade on tlie
dorsal side and extending to the epidermis. Ducts (on the ventral
side) frequent just beneath these extensions.
Mestome bundles of the veins (fig. 49) lying deep in the water-storage
tissue; reinforced on the leptome side b}' a strong group of very thick-
walled stereome, on the hadroine side by a smaller group; leptome
and its elements beautifully differentiated, the sieve tubes each witli
water-storage tissue in the interior of the leaf and the absence of hairs— just the
converse of what one would expect as the differential characters between a dune
and a salt-marsh species.
' The apical cells are easily broken off, so that in older leaves the covering appears
to consist of rounded, usually biceliular papillae.
310
THE PLANT COVERING OF OCRACOKE ISLAND.
a companion cell and a band of four or five cribrile parenchyma
cells. 1
Leaf anatomy of salt-marsh species.
[The sign x indicates presence of character; ±
Its imperf
ect development.]
Leaf.
Epidermis.
Cuticle.
Ul
Species.
i
t
2
1
-2
Relatively
thick.
Thick.
1
■S
H
it
X
X ■ X
X
X
X
X X
X
Titjcifl marina
X
X
Kosteletzkya virginica
X
±
Vincetoxicum palustre
X
X
X
X
X
X
X
X
X
Lippia nodiflora
±
X
I
X
X
X
±
Iva frutescens
X
X
X
X
X
X
X
X
Aster tenuifollus
Baccharis halimifolia
X
X
X
Characters given under species of the "sand strand," page
1 Borrichia arhorescens (compare Warming, Halofyt-Studier, p. 212) is a very-
similar but larger plant of the tropical American strand. It differs from B. frutes-
cens in the following particulars, the characters being taken from material col-
lected in South Florida and Porto Rico:
Hairs much thicker-walled, entirely disappearing in old (more than 1 year
old?) leaves; stomata on both surfaces, with guard cells slightly prominent on the
ventral face, less numerous and with guard cells slightly sunken on the dorsal
face; epidermal cell walls, especially the outer, thick; palisade interrupted both
above and below by extensions of the water-storage tissue, which on the ventral
side ultimately disorganize and form large lacunes; hypodermal coUenchyma
occurring where the palisade is interrupted on the ventral side; coUenchyma
taking the place of stereome as supports of the veins, especially strong on the lep-
tome side.
From Warming's description and figure of B. arhorescens my specimens showed
important differences: (1) The presence of hairs (elsewhere in the same paper
Warming mentions their occurrence in this species) ; (2) stomata with guard cells
slightly prominent on the ventral surface (Warming writes "stomata sunken"");
(3) coUenchyma present and strongly developed; (4) mestome bundles in three
planes (one according to Warming) , some small ones being situated near the upper
and the lower epidermis, while the midvein is central in the water-storage tissue.
ANATOMICAL SUMMARY OF SALT-MAKSH SPECIES.
311
Leaf anatomy of salt-inarsh .s^«'c/V.s — ( ontiuned.
[The sign x indicates presence of character; ± its imperfect development.]
.
Epidermis.
Stomata.
Species.
1
1 •
•if
1
1 .
^1
cc
^ .
1
i
0
1
0 .
■>-' Cfi
i
•a
!
u
1
Triglochin striata
X
X
X
X
Spartina stricta '
J uncus roemerianus .
X
X
X
i
X
Tissa marina
X
X
X
X
Kosteletzkya virginica
X
X
X
X
X
X
X
X
X
X
Ammania Ivoehuei
±
Vincetoxicum palustre . . .
X
Lipi)ia nodiflora -..
±
X
Monniera monniera
X
Iva f rutescens - -
X
X
Solidago sempervirens
X
Aster tenuif olius
X
X
i
Aster subulatus.
X
Baccharis halimifolia
X
Borrichia f rutescens
X
Epidermis.
Hypoder-
mal collen
chyma or
collenchy-
matic tissue.
Hairs.
Species.
eg
U
Is
f
1
1
1
IS
1
cc
c
1
i
"O U
0 o
3
1
la
a
O
2
Triglochin striata
Spartina stricta '
Juncus roemerianus . .
Sesuvium maritimum. .
1
Tissa marina
X
X
X
X
Kosteletzkya virginica
>^'
X
X
Ammania koehnei- .
Vincetoxicum palustre
Lippia nodiflora
X
X
X
X
Monniera monniera
Iva f rutescens...
X
X
X
X
X
X
X
Solidago sempervirens
Aster tenuifolius
Aster subulatus
Baccharis halimifolia ..
X
Borrichia frutescens. . .
X
X
X
X
■
1
^ 1
1 Characters given under sjiecies of tlio "sand strand." page
312
THE PLANT COVERING OF OCKACOKE ISLAND.
Leaf anatomy of salt-marsh spec/'e.s— Continued, ♦
[The si^a x indicates presence of character; ± its imperfect development.]
Stereome.
Water
Chlorenchyma. paren-
chyma.
Mestome
bundles.
Species.
1
1
05
1 .
t
I
o
W
t
(D
4i
H
ll
II
be
.S
II
1
it
5 .
a®
1
2
03
ft"'
X
X 1 X
Sioartina stricta^
Juncus roemerianais...
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Kosteletzkya virginica.
X
X
X
Vincetoxicum palustre
X
±
X
X
X
X
X
X
X
X
Solidago sempervirens.
X
X
X
X
X
X
X
X
X
X
X
X
1
1 Characters given under species of the "sand strand," p. 389.
GEOGRAPHICAL AFFINITIES OF THE FLORA.
According to its geographic position, Ocracoke Island lies well
within the Anstro riparian area of the Lower Austral life zone in North
America.^ For two reasons, however, this relationship of its flora is
somewhat obscured: (1) By the large proportion of strand species,
many of which have a very extensive geographic range; and (2) by the
absence of many of the most characteristic species of the Austro-
riparian area, due to the peculiar physical environment.
Of the total number of species of embryophytes (about 135) collected
or observed upon Ocracoke Island, between one-fourth and one-third
may be designated as maritime, i. e., normally occurring only in the
salt marshes or on the sand strand bordering the ocean. These may
be segregated into 4 groups, according to geographical range :
1. Species occurring also on the coasts of tropical America.
A prefixed asterisk (*) indicates that the species does not extend
north of the mouth of Chesapeake Bay; a prefixed dagger (f) that
the northern limit is in North Carolina, probably not far from Ocra-
coke. Triglochin striata and Monniera monniera extend north to
eastern Maryland.
'Merriam, Geogr. Distrib. p. 211: Life Zones p. 45, map.
GEOGRAPHICAL AFFINITIES OF THE FLORA. 313
Triglochin striata R. & P. \ Yucca aloifolia L.
*Qaercus vir-ginianaLi.^ * Physalis viacosa ^L.
\Chloris petraea Sw. Monniera monniera H, B. K.
* Uniola xKinicuUda L. *Borrichia frutescena L.
^Fimbristylis spadicea Vahl. \Ipomoea sagittata Cav.
2. Species mostly or entirely confined to the seacoast of the Austro-
riparian area: Zdidhoxyluni dava-lievculis and, X)ossibly, Ilex roini-
toria extend northward to Virginia, while the rest attain their northern
limit in North Carolina.
Miihlenbergia filipes M. A. Curtis. Ilex vomitoria Ait.
Yucca gloriosa L. Opuntia pes-corvi Le Conte.
Croton maritimus Walt. Vincetoxicum palustre (Pursh) A. Gray.
Zanthoocylum clava-herculis L.
3. Species confined to the Atlantic seacoast of North America and
ranging north of the Austroriparian area. The northern limit of
each is cited as given in Britton & Brown's Illustrated Flora.
Panicum amarum minus Vasey & Oenothera humifusa Nutt. (New Jer-
Scribn. (Connecticut). sey).
Spartina patens (Ait.) Muhl. (Nova Limonium earolinianum (Muhl.) Brit-
Scotia), ton (Labrador).
Distichlis spicata (L. ) Greene - (Maine) . Iva frutescens L. (Massachusetts) .
Juncus roemerianus Scheele (New Jer- Solidago sempervirens L. (New Bruns-
sey). wick).
Sesuvium maritimum (Walt.) B. S. P. Aster tenuifolius h. (Massachusetts).
(New York). Aster siibidat us Michx. (New Hamp-
Euphorbia polygonifolia L. (Rhode shire).
Island). Baccharis halimifolia L. (Massachu-
Kosteletzkya virginica L. (New York). setts).
Ammania fcoe/mei Britton (New Jersey).
4. Species occurring also on the seacoast of the northern hemisphere
in the Old World.
Spartina stricta (Ait. ) Roth. Salsola kali L.
Atriplex hastata Ij. Tissa marina {Ij.) Britton.
Salicornia herbacea L.
Of the nonmaritime species of the island, fifteen are introduced
and are chiefiy weeds of American origin. The remainder (about
two-thirds of the total flora) includes several mainly tropical species,
such as Lippia nodiflora Michx., Centella asiatica (L.) Urban, Parietn-
ria deb His For St., and Tillandsla tts?ieoidesL., which, while hardly mari-
time, are found usually near the seacoast in the Austrorix)arian area.
Finally, after excluding all the preceding categories except the second
of strand plants, we have a list of species among which the Austro-
riparian element is sufficiently predominant to leave no question as
to the general affinity of the flora.
As previously remarked, however, many of the plants most cliar-
' Normally a strand plant in Virgfinia and North Carolina.
-The typical form.
314 THE PLANT COVERING OF OCKACOKE ISLAND.
acteristic of the whole Austroriparian area, and abundant on the
mainland, scarcely 30 kilometers distant, are wanting upon Ocracoke
Island. Notable among these absentees are the pines {Pin uspalustris^
P. taeda), the gums (Xyssa spp.), the bald cypress {Taxodiuin dis-
tichum), the deciduous oaks, the cane (Arundinaria macrosperma),
species of Erianthus, Carex verrucosa, Smilax laurifolla, and Bei^-
chemia scandens. Hardly less striking is the nonoccurrence of most of
the bright- flowered herbs that abound in the pine forests on the west
shore of Pamlico Sound. Such are species of Coreopsis, Helianthus,
Lacinaria (Liatris), Eupatorium, Solidago, Rhexia, Gerardia, H3^i3er-
icum, Sarracenia, Habenaria, and Polygala. The unfavorable environ-
ment is doubtless responsible for the absence of many of these plants,
conditions ui)on the island being suitable only to tlie hardiest species.
Scarcity of shade, of humus, and of fresh water accounts in like man-
ner for the poverty of the flora in most of the lower forms, such as
fresh-water algae, fungi, hepaticae, mosses, and ferns. The numerous
arrangements b}^ which many of the higher plants are protected against
excessive loss of water maj^ also serve in some measure for protection
against parasitic leaf fungi, and may partly account for the com-
parative scarcity of the latter.
The general aspect of the j)lant covering is not attractive. Bright
green foliage and flowers of brilliant coloring are too scarce to make
much impression, while, except in the salt marshes, the plants are
usually so scattered that it is the soil which gives tone to the land-
scape. Furthermore, the trees and shrubs are mostly characterized
by gnarled trunks, many dead branches, and ragged foliage, as a
result of exposure to sand-laden winds. Altogether, the picture is
one of somber monotony.
LIST OF PLANTS COLLECTED AND OBSERVED.
[The prefixed asterisk denotes that the plant is introduced.]
LICHENES.
Usnea barbata L.
Ramalina tnontagnei De Not.
MUSCI.
Bryum argenteum L.
Rhynchostegium serrulatum Hedw.
POLYPODIACEAE.
Aspleniuin platyneuron (L.) Oakes. {A. ebeneumA.it.)
PINACEAE.
Juniper us virginiana L.
TYPHACEAE.
Typha latifolia L.
SCHEUCHZERIACEAE,
Triglochin striata Ruiz & Pav.
LIST OF SPECIES. 315
POACEAE.
Aridrojjogou glomeratus (Walt.) B. S. P. (A. laacronriis Michx. ;
Paspalum ciliatifoUmn Michx.
PaHpalam distichum L.
Paspalum laeve JNlichx.
Syntlierisviafiinbriata (Smith) Nash. (Digitaria Jivihr'tafa Smith.)
PauicKiii ainarum minus Vasey & Scribner.
Pauicuiii lattuginosum Ell. (?)
Panicuiu laxijlorum Lam.
Panicum neuranthum Griseb.
Panic um walteri Pursh.
OjjI is menus setarius (Lam.) Roem. & Schult.
Chaetochloa imherbis pereiinis (Hall) Scribn. & Merrill. (C. versicolor
Bicknell.)
Homalocenchrus virginicus (Willd.) Britton. ( Leers ia virginica Willd.)
MuhlenhcrgiafilijjesM. A. Curtis.
"^Sporobolus indicus (L.) R. Br.
*Capriola dactylon (L.) Kuntze. {Cynodon dacftjlonPeia.)
Spartina patens {Ait.) Muhl. {S. jancea'EAl.)
Spartina stricta (Ait.) Roth.
Chloris p>etraea Sw.
*Eleusine indica (L.) Gaertn.
Triplasis purpurea (Walt.) Chapm.
Eragrostis nitida (Ell.) Chapm.
Uniola laxa (L.) B. S. P. {U. gracilis Michx.)
Uniola paniculata L.
Distichlis spicata (L.) Greene. (D. maritima Raf.)
CYPERACEAE.
Cyperus cylindricus (Ell.) Britton. (C. torreyi Britton.)
Cyperus echinatus (Ell.) Wood. (C haldwinii Torr.)
Cyperus nuttallii Eddy.
Cyperus speciosus Vahl.
Eleocliaris sp.
Dickromena colorata (L.) A. S. Hitchcock. (7). leucocephala Michx.)
Fimbristylis spadicea (L.) Vahl.
Scir2)us americanus Pers. {S. pungens Vahl.)
Scltria verticillata Muhl.
Cladium effusiwi Torr.
ARACEAE.
Acorus calamus L.
Tillandsia usyieoides L.
BROMELIACEAE.
JUNCACEAE.
Juncus dichotomus Ell.
Juncus roeinerianus Scheele.
Juncus scirpoides Lam.
LILIACEAE.
Yucca aloi folia L.
Yucca gloriosa L.
SMILACEAE.
Smilax bona-no,v h. (S. tamnoidoi A. Gray.)
31(J THE PLANT COVERING OF OCRACOKE ISLAND.
MYRICACEAE.
Myrica ca^'olinensis Mill.
Myrica cerifera L.
FAGACEAE.
Quercus virginiana L. {Q. virens Ait.)
MORACEAE.
* Ficus carica L.
* Brousso7ietia pajyyrifera (L.) Vent.
URTICACEAE.
Parietaria debilis Forst.
POLYGONACEAE.
Polygonum punctatum Ell.
Rumex sp.
CHENOPODIACEAE.
* Chenopodium anthelminticum L.
Atriplex hastata L.
Salicornia herbacea L.
Salsola kali L.
PHYTOLACCACEAE.
Phytolacca decandra L.
AIZOACEAE.
Sesuvium maritimiim (Walt.) B. S. P. {S. pentandrum Ell.)
Mollugo verticillata L.
ALSINACEAE.
Tissa marina (L.) Britton. (Spergularia salina J. & C. Presl.)
ROSACEAE.
Ruhus trivialis Michx.
CAESALPINACEAE.
* Cassia occidentalis L.
VICIACEAE.
Aeschynomene virginica (L.) B. S. P. {A. Iiispida Willd.)
Meihomia paniculata (L.) Kuntze. (Desmodium paniculatum DC)
Oalactia volubilis (L.) Britton. {G. pilosa Ell.)
LINACEAE.
Linum medium (Planch. ) Britton.
RUTACEAE.
Zanthoxylum clava-hercidis L.
EUPHORBIACEAE.
Croton maritimus Walt.
Acalypha gracilens A. Gray.
Euphorbia polygonifolia L.
ANACARDIACEAE.
Rhus radicans L.
LIST OF SPECIES. 317
ILICACEAE.
Ilex glabra (L. ) A. Gray.
Ilex opaca Ait.
Ilex vomitoria Ait. (/. cassine Walt.)
VITACEAE.
Vitis aestivalis Michx.
MALVACEAE.
Kosteletzky a virgin! ca (L. ) A. GJ-ray.
Hibiscus moscheutos L.
* Gossypium herhaceurn L.
HYPERICACEAE.
Ascyrum hypericoides L.
CISTACEAE.
Lechea villosa EW. {L. major Michx.)
CACTACEAE.
Opuntia pes-corvi Le Conte.
LYTHRACEAE.
Ammania koehnei Britt.
ONAGRACEAE.
Ludwigia alata Ell.
Ludwigia microcarpa Michx.
Oenothera huinifusa Nutt.
APIACEAE.
Sanicula sp.
Hydrocotyle umbellata, L.
Centella asiaticc (L.) Urban.
PRIMULACEAE.
Samolus florihundus H. B. K.
PLUMBAGINACEAE.
Limonium carolinianum (Walt.) Britton. {Statice limonium var. carolini-
aniun A. Gray. )
LOGANIACEAE.
Cynoctonum mwreola (L. ) Britton. {Mitreola petiolata Torr. & Gr.)
Polypremum procumbens L.
ASCLEPIADACEAE.
Vincetoxicum palustre (Pursh) A. Gray. {Seiitera maritima Decne.)
CONVOLVULACEAE.
Ipomoea sagittata Cav.
VERBENACEAE,
Lippia nodiflora Michx.
Callicarpa americana L.
61 ri THE PLANT COVEKING OF OCRACOKE ISLAND.
NEPETACEAE.
Teucrimn nashii Kearney.
Monarda punctata L.
SOLANACEAE.
Physalis viscosa L.
Solanum caroUnense L.
* Solarium nigrum L.
. * Lycopersicum esculentum L.
* Datura tatula L.
SCROPHULARIACEAE.
*Verbascum thapsusJj.
Monniera monniera (L. ) Britton. {Herpestis monniera H. B. K.)
Gerardia maritima Raf .
RUBIACEAE.
Oldenlandia uniflora L. (O. glomerata Michx.)
Diodia teres Walt.
Diodia virginiana L.
Galium sp. (probably G. tinctorium L. or G. claytoni Michx.).
CUCURBITACEAE.
* Citrullus vulgaris Schrad.
Melothria pendula L.
CICHORIACEAE.
Hier actum gronovii L.
CARDUACEAE.
Elephantopus nudatus A. Gray.
Mikania scaudeiis (L.) Willd.
SoUdago sempervirens L.
Euthamia caroliniana (L.) Greene. {SoUdago tenuifolia Pursh.)
Aster salicifolius Lam. var.
Aster subidatus Michx.
Aster tenuifoliris L.
Erigeron canadensis L.
Baccharis halimifolia L.
Pluchea camphorata (h.) DC.
Phichea foetida (L.) B. S. P. (P. bifrons DC.)
Gnaphalium purpureum L.
Ambrosia artemisiaefolia L.
Iva frutescens L.
Xanthium sp.
Xantliium sp.
Borrichia frutescens L.
^Bidens bipinnata L.
Ereclitites liieracifolia (L.) Raf.
Carduus spinosissimus Walt. {Cnicus horridulus Pursh.)
Library
N. estate College
WORKS REFERRED TO. 319
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Diels, L. Stoffwechsel und Structur der Halophyten. Jahrbiicher fiir wissen-
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Duval-Jouve, M. J. Etude Anatomiiue de quel(iues Graminees. Memoires de
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Duval-Jouve, M. J. Etude histotaxique des Cyperus de France, Memoires de
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