OF CEYLON AND INDIA. 
341 
2,000 feet, especially in the Mahaweli and Kelani rivers. It 
grows, as a rule, in rapidly running broken water, but not in 
such violent streams as does Lawia. Its size and its manner 
of drifting out with the current cause it to afford a much 
greater hold for the water to pull upon. It is most often 
found growing by itself, like most of these plants, but is 
commonly found mixed with Podostemon subulatus or 
Dicræa stylosa, var. laciniata, less often with var. fucoides, 
or with Hydrobryum olivaceum. It is usually one of the 
first to emerge as the water-level falls. 
Dry Season Appearance . — As found in January or February 
upon dry rocks the plant consists of numerous more or less 
upright or projecting woody stalks, reaching to a length of 
about 10-15 cm., with distichous stalked fruits borne at 
intervals of about 1 cm. on each side. Along the rock, and 
firmly attached to it, are Avoody creeping thalli, from Avhicîi 
the erect ones spring. The erect stalks are also thalli, while 
the lateral stalks borne upon them are the secondary shoots, 
endogenously formed from them and bearing each one fruit 
(PI. XIX.). Usually some plants may be found which are 
still submerged, and then it can be seen that the erect woody 
thalli are only the lower ends of very long thalli, which drift 
out in the water to a length of as much as 50 cm., bearing 
little fascicles of leaves towards the outer end, and fioral 
shoots on the lower parts (PI. XIX., and cf. figs, in Tulasne 
and Warming). 
Germination and Life History . — The seed has the usual 
structure, with a mucilaginous outer coat, and the germina- 
tion takes place as in those species already described. The 
cotyledons spread out approximately in the same plane, but 
sometimes with a tendency to approach one another on one 
side and thus give the embryo an asymmetrical structure. 
Almost at once the leaves of the primary axis appear. The 
first and second are usually, but apparently not always, 
nearly at right angles to the plane of the cotyledons (PI. 
XYIII., fig. 1), and they are folloAved by a small number of 
other leaves, which are arranged in no very exact order or 
