328 WILLIS : MORPHOLOGY OF THE PODOSTEMACEÆ 
of root nature, very similar to that of Tristicha ramosissima, 
attached to the rock by hairs and haptera, and with endo- 
genous branching and a root-cap. From this are given off, 
often more or less paired, the secondary shoots, which grow 
upwards to a greater or less height, bear distichous leaves, 
branch more or less often, and bear several or many flowers. 
The early stages in the life-history, even of such com- 
paratively accessible forms as the Ohio P. Ceratophyllum, are 
however completely unknown. 
PodostemoBi subulstftus, Gardn. 
(Plates XIV.-XVI.) 
I have investigated this species chiefly at Hakinda, where 
it is abundant, and I have also found a variety of it in the 
Anamalai mountains. The latter is characterized by smaller 
habit and longer pedicels, and may perhaps ultimately prove 
specifically different. 
Habitat . — In Ceylon the plant occurs in the Mahaweli- 
ganga and its tributaries, between 1,500 and 2,000 feet. At 
Hakinda it is common, and presents a very striking appear- 
ance, especially when seen in the height of the vegetative 
season in September. It grows like the rest only on a rock 
substratum, and is rarely found in rapidly moving or broken 
water, but occurs in great masses in the more quiet bays in 
the rocks among the rapids, where the eddy keeps the water 
in constant slow movement past the plants, waving the long- 
red or green leaves to and fro, like Algæ on the rocks of a 
quiet seabeach. Like the rest it is never found on unstable 
substrata or in stagnant water. It is very often mixed with 
Dicræa elongata, more rarely with D. stylosa, vars. laciniata 
or fucoides, or with Farmeria metzgerioides, and occasionally, 
at places where an eddy returns into the main rush of the 
stream, it occurs mixed with Lawia zeylanica or Hydrobryum 
olivaceum. Its habitat in the one place where I found it in 
the Anamalais was very similar ; it was not mixed with any 
other species, but close to it, at the edge of the eddy in which 
it grew, were Willisia selaginoides and a Hydrobryum. 
