The epidermal structure of the leaf and stem of Ephedra foliata Boiss. is described. The epidermis of internodes and leaves shows longitudinal rows of cells and stomata. In the nodes and the leaf bases the stomata are irregularly orientated. The subsidiary cells are perigene and the development of stomata is typically haplocheilic

Mehra, Bharati

Pant, D. D.

English

Publications of the IAS Fellows

EPIDERMAL STRUCTURE AND DEVELOPMENT OF
STOMATA IN EPHEDRA FOLIATA BOISS.
BY D . D . P A N T AND B H A R A T I M E H R A
Department of Botany, The University,
Allahabad, India
{Received z August 1963)
SUMMARY
The epidermal structure of the leaf and stem of Ephedra foliata Boiss. is described. The
epidermis of internodes and leaves shows longitudinal rows ojf cells and stomata. In the nodes
and the leaf bases the stomata are irregularly orientated. The subsidiary cells are perigene and
the development of stomata is typically haplocheilic.
INTRODUCTION
Various descriptions of the ontogeny of stomata in the living gymnosperms are available.
These include accounts of the haplocheilic development of stomata in certain conifers
by Florin (1931), in Gnetum gnemon and G. ula by Maheshwari and Vasil (1961), and
in three species of Cycas and Ginkgo biloba by Pant and Mehra (1964). Syndetocheilic
development of stomata has been reported in Gnetum gnemon and Welwitschia mirabilis
by Takeda (1913a, b, respectively). A genus of modern gymnosperms whose stomatal
ontogeny remains uninvestigated is Ephedra. Accordingly, in the present paper the
authors have described the development of stomata in the common Indian species, E.
foliata. The material was collected from a plant cultivated in the Botanical Garden of
the Allahabad University.
RESULTS
The adult epidermis
The epidermis of mature internodes is ridged and consists of longitudinally elongated
epidermal cells (Figs, i and 3) which tend to be in rows parallel to the long axis
of the stem. The size of the epidermal cells varies considerably but those of the nodal
region tend to be shorter and are often wider than long. The epidermal bands above the
ridges are non-stomatiferous and are of somewhat larger cells with papillae on their
surface. The form and size of the papillae is very variable, e.g. in the ridges of the
internodes of the plant a papilla may usually appear as a short local bulge of a cell where
its cuticle is thickened but just above a node, usually on its side which faces a leaf, the
papillae tend to be more elongated becoming long tapering and hair-like near the leaf
base (Fig. 4). Their rounded tips are directed downwards and occasionally somewhat
swollen. Cauline stomata are usually confined to the furrows. In the internodes the
stomata are typically placed in longitudinal rows and those of adjacent rows are often
alternating (Fig. i). In the nodal region the stomata may be irregularly or even trans-
versely orientated (Figs. 4 and 5). The stomatal index is 22.
Some of the cells of the upper (adaxial) epidermis of a leaf (Figs. 10 and 11) are
91
92 D. D. PANT AND BHARATI MEHRA
papillate, but near the leaf base practically every cell is papillate (Fig. i i ) and there are
also a few long papillae at the tip of the leaf (Figs. 12 and 13). Papillae of the foliar
epidermis are usually directed upwards towards the tip of the leaf. They arc normally
inserted at or near the distal end of each epidermal cell. Stomata occur on both sides.
.
Fig. I. Cuticle of an internode showing somewhat larger papillate cells over the ridges and
an intervening stomatiferous area in the region of a furrow. . ioo.
Figs. 2 and 3. Mature stomata from a leaf base and an internode, respectively. Guard cell
outlines, which are overlapped by subsidiary cells, are shown by dotted lines. The centripetal
sides of subsidiaries are thickened and somewhat papillate. The subsidiaries in Fig. 2 are
irregular but those in Fig. 3 are differentiated into two polars and two laterals. Fig. 2. x 750;
Fig. 3, y 600.
Figs. 4 and 5. Cuticles from the lower extremity of an internode and a node, respectively.
Jrinta'ted^'Zh 12*5." '^ ' '"*^ * ' '*' '" '^ ' ' '"'" irregularly o^  transversely
of the leaf but their number decreases steadily towards the base where there are practi-
cally none on the upper side. Stomata occur almost up to the leaf apex (Figs 12 and 13).
Foliar stomata are longitudinally orientated over the lamina but near the leaf base they
tend to be irregularly placed.
Stomata of Ephedra 93
The structure of the mature stomata of Ephedra is well known (cf. Thompson, 1912;
Pearson, 1929; Florin, 1933). In E. foliata the guard cells are 36-57 ^ long/10^21 \x
wide (mean 45 ±z x 17^3 v). The stomata are usually evenly spaced but they may be
occasionally contiguous in the stems as well as in the leaves (Fig. 9). The guard cells
are generally surrounded by four but sometimes five and rarely more, rather slightly
specialized subsidiaries which differ from the ordinary epidermal cells only in having
the sides towards the stomatal pore slightly thickened and often somewhat papillate.
The four subsidiaries of the stomata in the internodes and leaves are usually differentiated
into two polars and two laterals but there is no such differentiation in the stomata of
the nodes and the leaf bases (Fig. 2). The stomatal index in the middle region of the
upper epidermis is 18 and that of the lower is 24.
Fig. 6. Protoderm cells of a stem near apex showing a stomatal meristemoid (darker stippled).
X 750.
Fig. 7. Epidermis of a stem near apex showing a meristemoid at anaphase. / 750.
Fig. 8. Epidermis of a young stem showing freshly formed guard cells without the intervening
pore. X 750.
The cuticle of the stems and leaves, prepared by macerating them with Schulze's
fluid, shows clear cell outlines and longitudinal striations or cutin folds. The striations
are especially clear on the surface of marginal cells of the leaf lamina, over the cells of
the ridges of the stem and on the surface of papillae.
The epidermal structure of the leaves and stems of E. foliata resembles that of many
species of Cordaites. Besides showing a general similarity in having stomatiferous and
non-stomatiferous bands lying parallel to the long axis, the stomata of Ephedra foliata
resemble those of Cordaites borassifolius, C. angiilosostriatus, C. mansfieldi, C. serpens,
C. prindpalis and others in having similar, poorly specialized, subsidiary cells (Harms
and Leisman, 1961; Pant and Verma, unpublished) which tend to be papillate on the
side of the stomatal pore. Indeed, the epidermal structure oi Ephedra foliata and Cordaites
leaves is so similar that it may be cited as an additional argument in support of the
cordaitean affinities of Ephedra (Eames, 1952; Pant, 1957).
Development of stomata
Epidermal peels of young portions of the stems and leaves were stained in aceto-
carmine. They show short, irregularly placed, isodiametric, polygonal cells with straight
anticlinal walls and, here and there among them, meristemoids (guard cell mother cells)
may be distinguished by their deeper stain and rectangular shape (Fig. 6). The nucleus
of a meristemoid divides only once (Fig. 7) and usually a longitudinally placed wall
94 D. D. PANT AND BHARATI MEHRA
subsequently partitions it into two cells. This results in the formation of two guard cells
which are at first small, flush with the surface and without an intercellular gap between
them (Fig. 8). The subsidiaries are formed by protoderm cells which happen to surround
the meristemoid. Protoderm cells, other than the meristemoids, may also divide but they
11
Fig. 9. Two contiguous stomata from near the apex of a leaf 200
Figs 10 and I I . Cuticles from the middle and basal parts, respecti'velv, of leaves. Non-
papillate portions, on the right in Fig. lo and on the left in Fig. 11 represent the cuticle of
on ' thX." d" ^ W T" ''t ^^^--P^P^"^^^ '^'''''^-' « " - The?requency o " otaton the lo^er side is higher in the middle region (Fig. 10) than near the base (Fig. 11) but
Both 125. ' ' ' " ' ° ' ' ' '^un^e^us and larger in the basal part than in the middle region.
Figs. 12 and 13. Cuticles from the apices of leaves showing larger papillae in cells at their
tips. Note the occurrence of stomata up to very near the apex. Both ^^125.
generally form transverse walls and their daughter cells develop into ordinary epidermal
? u u^T '" ' " ' ' ' ' ' ^ ' °^^^' ^ ' ' ^ ^ ' ' ' ^"^ "°^^1 epidermis may divide in any direction.
As the subsidiary cells enlarge and mature they grow over the guard cells. The guard
cells ultimately become kidney shaped and a stomatal pore appears between them
Stomata of Ephedra 95
CONCLUSION
This study of the development of stomata in Ephedra foliata shows that its guard cell
mother cells and subsidiaries do not develop from an immediately preceding common
parent cell and thus confirms their haplocheilic nature (Florin, 1933) which, hitherto,
was concluded merely from the appearance of the adult stomatal apparatus.
ACKNOWLEDGMENTS
We are grateful to Professor T. M. Harris, F.R.S. for his critical suggestions atid help.
We are also grateful to Dr. D. D. Nautiyal for his ready help. Our thanks are due to the
Council of Scientific atid Industrial Research, India, for financial aid.
REFERENCES
EAMES, A. J . (1952). Relationships of the Ephedrales. Phytomorphology, 2, 79.
FLORIN, R. (1931). Untersuchungen zur Stammesgeschichte der Coniferales und Cordaitales. Morphologie
und Epidemiisstruktur der Assimilationsorgane bei den rezenten Koniferen. K. Svenska Vetensk Akad.
Handl., 10, I.
FLORIN, R. (1933). Studien iiber die Cycadales des Mesozoikums. K. Svenska Vetensk Akad. Handl., 12, i.
HARMS, V. L. & LEISMAN, G . A. (1961). The anatomy and morphology of certain Cordaites leaves. J.
PalenntoL, 35, 1041.
MAHESHWARI, P. & VASIL, V. (1961). The stomata of Gnetum. Ann. Bot., Lotid., N.S., 25, 313.
PANT, D . D . (1957). The classification of gymnospermous plants. Palaeobotanist, 6, 65.
P.'VNT, D. D. & MEHRA, B . (1964). Development of stomata m leaves of three species of Cycas and Ginkgo
biloba L. J. Linn. Soc, Lond. (In press).
PEARSON, H . H . W . (1929). Gnetales. Cambridge.
TAKEDA, H . (1913a). Development of stomata in Gnetum gnemon. Ann. Bot., Lond., 27, 347.
TAKEDA, H . (19136). Some points in the anatomy of leaves of Wekoitschia mirabilis. Ann. Bot., Lond.,
THOMP'SON^W. P . (1912). The anatomy and relationships of the Gnetales. i. The genus Ephedra. Ann.
Bot., Lond., 26, 1077.
N.P. G



Epidermal structure and development of stomata in Ephedra foliata Boiss.

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