204 
WILLIS : PODOSTBMACBÆ 
alternate with perianth segments, in irregular flowers 1-3, 
usually 2, monadelphous on the lower side of the flower, 
the common stalk usually much exceeding the partial 
fllaments. Staminodes or abortive perianth segments in 
zygomorphic flowers usually 2, filamentous, on either side 
of andrœceum, with sometimes a third between the partial 
filaments. Anthers introrse, 2-locular. Pollen grains 
didymous in zygomorphic flowers. Ovary superior, usually 
more or less ellipsoid, often oblique, 3- or 2-locular with 
thick central placenta and very delicate septa ; the outer wall 
usually smooth or only very faintly ribbed, often with deci- 
duous cortex. Ovules anatropous, usually oo , and very minute, 
few and larger in Farmeria. Stigmas as many as carpels, 
sessile, subulate, dentate, or cuneate, often lobed. Capsule 
usually pedicellate, the pedicel of the flower lengthening 
after fertilization and at the same time becoming woody 
and losing its deciduous pellucid cortical tissue, ribbed or 
smooth, septifragal (closed in one sp. of Farmeria), with 
equal or unequal lobes, in the former case both, in the latter 
the larger, persistent on the pedicel after dehiscence. Seeds 
usually ao , small, with mucilaginous outer coat. Endos- 
perm 0. Embryo straight, simple. 
Herbs of rapids and waterfalls in mountains of India, 
Burma, and Ceylon, usually annual, submerged, and closely 
attached to the rocks, flowering when exposed in the dry 
season by the fall of the water level, with the habit and 
structure of algæ, lichens, mosses, and liverworts. Germi- 
nation with the onset of the rains. Primary axis various, 
early giving rise to a thallus, in Lawia composed of flattened 
shoot, in the other genera of a root structure which assumes 
various forms, thread-like, ribbon-like, disc-like, cup-like, 
&c., attached to the rock at all points or only at the centre, 
or at the centre and two or three outer points, bearing 
the leafy endogenous secondary shoots on the margins or on 
the upper surfaces. Secondary shoots leafy only in the 
vegetative season ; leaves usually more or less distichous, 
except in the Chlamydatæ, simple, usually sheathing, often 
