FAMILY OF FLOWERING PLANTS. 53 
Ovary superior, ellipsoid, of 2-3 carpels, 2-3-locular, with thick central 
placenta, delicate septa, and «o anatropous, horizontal, ascending ovules : 
stigmas usually sessile, as many as carpels (style in Weddellina). Capsule 
stalked, ribbed (usually conspicuously), septifragal, with equal lobes usually 
persistent upon the pedicel after dehiscence. Cortex of pedicel and capsule 
usually deciduous. Seeds оо, small, exalbuminous, with straight embryo, 
mucilaginous if wetted. 
Herbs living on rocks in rapidly moving water, usually annual, but 
persisting if not exposed to the air, flowering with the fall of the water-level 
in the drier season, germinating with the rise of the water. Roots fila- 
mentous, creeping over the rock, branching freely, attached by root-hairs 
and haptera, and giving rise to endogenous secondary shoots at frequent 
intervals (Lawia has no roots, the thalloid shoot being the primary axis). 
Secondary shoots long, much branched, or flattened into thalli. Branches 
often of two kinds, one normal, the other ramuli or shoots of limited growth, 
sometimes with tristichous leaves. Leaves small, delicate, moss-like, simple, 
usually entire, exstipulate. Flowers terminal, sometimes on special shoots. 
The family includes the following genera and species : 
Tristicha hypnoides. Mexico to Uruguay; Africa trop: | Jide 
W 
" alternifolia. Africa trop., Madagascar. arming. 
» sp. nov. S. Brazil. 
5 ramosissima. N.W. India. 
Lawia zeylanica. W. India, Ceylon. 
Weddellina squamulosa. Guiana, North Brazil. 
PoposTEMACEG. Flower $, fully hypogynous, small or fairly large, incon- 
spicuous or brightly coloured, regular, slightly irregular, or highly 
zygomorphic, achlamydeous, enclosed before anthesis in a closed spathe 
springing from the base of the stalk, and opening at the tip or along the 
upper side. Stamens оо –1, in one or more whorls, free or united in one or 
more groups, regular or only on the lower side of the flower, usually with 
as many staminodes ; pollen often didymous in zygomorphic flowers. Ovary 
superior, ellipsoid, of two carpels, 2-1-locular, symmetrical or zygomorphic 
(often highly so), with thick central placenta and o or few (2-10) 
anatropous ovules, usually horizontal and more or less ascending ; stigmas 
usually as many as carpels. Capsule stalked or sessile, ribbed or smooth, 
dehiscent or indehiscent, with equal or unequal lobes. Cortex of stalk and 
capsule often deciduous. Seeds œ or few, exalbuminous, with straight 
embryo. Testa becoming mucilaginous when wetted. 
Herbs growing on rocks in rapid water, usually annual, but persisting if 
not exposed to the air, flowering with the fall of the water, germinating 
with the rise. Primary axis (? always) short, usually non-floriferous, giving 
