The Podostemaceae of India and Ceylon. 61 
majority of the Indian Podostemaceae they are much more 
reduced and bear small, sheathing leaves. The shoots of Tristicha 
are peculiar in that they develop numerous further shoots of the 
second order (ramuli). These latter are of limited growth, and bear 
smaller leaves than the main shoots. In the angle between these 
latter and the ramuli buds arise, many of which develop into shoots 
of unlimited growth, which repeat the structure of the main axis. 
Others of these buds, however, remain dormant till the flowering 
period, and then develop into floral shoots. In the other genera we 
observe a reduction in size of the secondary shoots, which goes 
hand-in-hand with the increasing dorsiventrality of the thallus ; 
at the same time the secondary shoots may themseves show a very 
marked dorsiventral structure. In Willisia sehurinoides it is note- 
o 
worthy that these shoots attain a considerable height (2—7 cm.) 
and stand stiffly out into the water, a strong band of lignified tissue 
around the central strand, enabling them to resist the force of the 
current. 
At the end of the rainy season, when the water begins to fall, 
the flowers are developed and by the time they get exposed to the 
air, they are ready to open. In all the flattened forms they are 
developed terminally on a secondary shoot, a number of the leaves 
being transformed into bracts by the falling away of their upper 
portions and an increased development of the base. In Lawia they 
are borne on special shoots, which arise from one of the many 
marginal growing points of the flattened thallus. In Tristicha 
their development on branches of the main secondary shoots has 
already been mentioned; in this genus they are only rarely found 
on secondary shoots, arising directly from the thallus. The anemo- 
philous flowers are generally destitute of a perianth (excepting 
'Tristicha and Latvia ), its place being taken by a closed spathe, 
which protects the young flower. In Farmeria and Hydrobryum 
sessile the flower is sessile, but it is usually provided with a short 
peduncle, which elongates considerably later on ; after the flowering 
is over the inner part of the cortex of the peduncle becomes thick- 
walled and strongly lignified and the outer thin-walled portion falls 
away entirely, leaving the ripe fruit standing on a much thinner 
pedicel than before and on a highly elastic one, which is probably 
of advantage in the dissemination of the .seeds. Another 
interesting adaptation is observed in some of the flattened forms at 
the time of flowering. In these only a certain number (generally 
about one-third) of the secondary shoots ultimately become 
