OF CEYLON AND INDIA. 
335 
persist on the stalk. The figure shows the construction of 
the typical Podostemon fruit. As the cross section of that 
of P. Barberi shows, there are eight ribs, of which the septal 
ribs are double ; dehiscence occurs by their splitting and 
the falling away of the septa. In Podostemon the ribs on 
the one half of the fruit run down into the pedicel (XVI., 12), 
while those of the other and deciduous half do not. The 
halves of the dehiscence rib unite with the rib next to them 
on each lobe. The process will be easily understood by a 
reference to the figures, which may be compared with those 
of Dicræa. 
The capsules open as soon as ripe if the air be dry, and the 
plant now presents the usual dry season appearance figured 
in PI. XIV., fig. 1, in which the persistent lobes of the open 
fruits can be clearly seen. 
Rejuvenescence . — Like Lawia, this species exhibits a great 
power of rejuvenescence, forming new shoots with great 
rapidity if any necessity arise, as through injury. When, 
as not infrequently happens in August or September, the 
water falls rather low during the vegetative season, many of 
the leafy shoots and parts of the thallus become exposed to 
the air and die. As soon as the water rises again, however, 
the tip of the thallus forms a new growing point, growth is 
resumed, and is soon as free as ever. This process also 
goes on in the dry season of February and March, when the 
bulk of the plant is killed by exposure ; branches of the 
thallus are formed and grow downwards over the rocks 
more rapidly than the water falls, so that the whole of the 
plant is not killed. It is rather hard, consequently, to say 
whether this plant, or indeed any of these plants, should be 
strictly termed annual. The new shoots formed in the dry 
weather of the early part of the year do not flower till the 
following dry season. 
This species is fairly well represented in herbaria : most 
of the specimens show leaves in situ on the stems, but only 
rarely show the thallus. 
