OF CEYLON AND INDIA. 
347 
a little twisted, so that one side is nearer the surface of the 
water than the other, then the flowers on this side will all 
open before those on the other side, and may even have 
ripened their fruits, while the flowers on the under side of 
the thallus are still in the bud. 
The flower is described and flgured by Warming ; in 
general it is very like that of Podostemon subulatus, already 
described and flgured above. It appears to be chiefly self- 
pollinated, like the other Ceylon forms, and practically all 
flowers set seed freely. The pedicel has the usual deciduous 
cortex. 
The fruit is very similar in structure to that of Podoste- 
mon, but has equal lobes. PL XVIII., flg. 12, shows the ovary 
in cross section ; it has the same wall structure and other 
features as in Podostemon, already considered, but on 
looking at the fruit in PI. XX., fig. 2, the essential difference 
between the two genera can be easily seen. In Dicræa the 
ribs are symmetrical on both lobes of the fruit, and from 
each lobe three ribs run down into the pedicel. The 
dehiscence rib is also symmetrically arranged, and the fruit 
splits accurately down the middle line into two equal lobes, 
which persists for some time on the stalk. As soon as 
exposed to the air, the non-floriferous parts of the thalli 
usually wither up and drop off, leaving the short woody 
fruiting stalks shown on the left hand in PI. XIX. 
Rejuvenescence.—Lil^Q the rest this species has a large 
capacity for regeneration of injured growing points and the 
production of new ones from almost any part of the thallus 
so long as submerged. The creeping thallus is able to stand 
considerable exposure without dying, and may revive and 
form new growing points. The process of regeneration of 
broken or injured tips has been described by Warming ; the 
new tip forms in the thallus a little way back from the 
injury, and growth is resumed. The creeping thallus also 
very readily gives rise to new growing points by endogenous 
(47) 
