47 
Flora of the Ceylon Littoral. 
bispinosa with its rosette of floating leaves forming a perfect mozaic 
on the surface of the water, a bladder on each petiole below the water 
serving to float the leaf, and much divided submerged leaves, 
was abundant here. Above the bridge the right bank of the river 
showed a constant succession of Sonneratia (bearing a Loranthus 
in places Acanthus and Chr it sodium, all with their bases covered 
by the water. Bruguiera occurred as a very occasional and only 
representative of the Rhizophoraceae. Behind were Phragmites 
and Cyperus, and further back the land was occupied by a padi (rice) 
field quite submerged at high water. Behind this again came the 
first solid ground with a belt of Calophyllum Inophyllum and then 
coconuts. Half a mile above the bridge the long-petioled ovate- 
cordate leaved A roid Colocasia antiquorum, a. typical river-side plant, 
which has long been cultivated everywhere for its edible starchy 
rhizome appeared, together with the narrow-leaved Susum anthel- 
minthcum. Sonneratia and Acanthus became less and less common, 
while Cyperus increased. Thus the tree vegetation becomes entirely 
re-placed by the typical tall river-side herbs (reed-marsh) vege - 
tation, mainly Cyperus, Colocasia, Phragmites, Acrostichum, fringing 
the low artificial banks or bunds separating the stream from the 
/>a<ff-fields which here line each side of the river. Here and there 
on the bund is an occasional tree of Sonneratia or Dolichandrone. 
This vegetation is quite parallel with the Phragmites-Typha- 
Scirpus formation fringing a river side at home, with an occasional 
alder or willow. Where solid ground came down to the river-bank 
Heritiera, Barringtonia, Pandanus, etc., were noticed. 
Thus the lower part of the river at Matara differs strikingly 
from that of Bentotta, at any rate at present. The essential 
difference is the practical absence of the Rhizophoraceae, and not 
far up the replacement of the tree-flora by a reed-marsh-flora 
separating the river from padi- fields. The first point is difficult to 
explain, but there seems no reason to suppose that the area occupied 
by padi would not naturally support mangrove-vegetation, and it 
appears reasonable to conclude that the tree-vegetation has been 
cleared to make room for padi, the bunds or low banks thrown up 
to protect the padi being afterwards colonised by the river-side 
herbs. 
Kalu Ganga. 
The river at Kalutara, the Kalu Ganga, may be described as a 
third example of estuarine vegetation ; it is very characteristic of 
