210 
WILLIS : PODOSTEMICEÆ 
frondose, branched, with rosettes of leaves endogenous on 
upper surface. Flowers c>o at apices of lobes, emerging 
from axial cupules covered with small leaves. Fruit 
9-ribbed. 
Perianth 3-fid, regular, imbricate, membranous, brownish-coloured, 
marcescent. Stamens 3, hypogynous, alternating with the segments of 
the perianth ; anthers 2-lobed, intforse, opening by longitudinal 
fissures ; filaments oval in section. Pollen globose. Ovary of 3 carpels 
syncarpous, superior, ellipsoid, obtuse, more or less 3-angled, 3- 
locular, with oo anatropous ovules on a thick axile placenta ; septa very 
thin. Stigmas 3, more or less linear, with large papillae, marcescent, 
simple. Capsule more or less enclosed in the persistent perianth, 1-3 
mm. long, ellipsoid to obovoid, 9-ribbed, 3-locular, septifragal ; 
valves 3, equal, opposite to the perianth, segments incurved after 
dehiscence, all ultimately deciduous. Seeds very numerous, minute, 
exalbuminous ; outer layer of testa becoming sticky when wetted. 
Embryo straight, with crumpled cotyledons. 
Herbs with frondose thalli, living on smooth rocks in rapids and 
waterfalls of the mountains of Western India and Ceylon, submerged 
in the period beginning with the onset of the south-west monsoon, and 
flowering in the dry season when exposed by the fall of the water 
Thallus closely attached to the rock, sub-orbicular or stellate, of shoot 
nature, rootless, attached by root hairs at all parts, usually much 
branched, with ribbon-like or fiabelliform lobes ; marginal growing 
points prostrate or slightly ascending. Leaves very numerous, simple, 
entire, usually acute, green or red with white-looking mesial line, very 
thin and delicate, and easily detached or broken in herbarium speci- 
mens : occurring in two positions, at or near the growing apices 
on the upper surface and edges of the thallus, and in closely packed 
endogenous rosettes on the upper surface of the older parts of the 
thallus. Leaves dimorphic at the growing points, the lateral ones 
broader and distichous, with the posterior margin uppermost, the 
upper ones linear and irregularly arranged ; size variable, from 1-16 
mm. long and to 3 mm. broad in the largest laterals. Older parts of 
the thallus leafless, except for the endogenous rosettes, but marked 
with scars of leaves. Flowers terminal on the growing points of the 
margins of the thallus, rarely on the upper surface, solitary, on pedicels 
emerging from terminal axial leafy cupules. Flowers radial in struc- 
ture, but cupules thicker and shorter on the upper side, more or less 
ascending, bristly in herbarium specimens. Floral axis sometimes 
almost or completely foliose. Leaves on lower side of cupule larger, 
distichous, as at vegetative apices. Pedicel at anthesis about 3-6 mm. 
long, covered, as also is the ovary, with a pellucid cellular cortex, 
which falls off after flowering, the inner tissues becoming lignified and 
forming an elastic pedicel to the fruit, 5-25 mm. long, erect. 
