IN CEYLON. 
421 
The effect of climate on the type of vegetation is well 
known. The rainfall may not, in parts of Ceylon, greatly 
exceed that of certain portions of Great Britain, yet the 
scarcity or abundance of it in certain areas determines 
whether a desert or jungle flora shall obtain. The low-lying 
trees, the production of small bushes, abundance of succu¬ 
lent leaved plants like Suæda maritima, Salicornia species, 
Portulaca quadrifida, L., and others which prevail along 
the north-west coast of Ceylon suggest how xerophytic 
vegetation may become when the rainfall is below fifty 
inches in tropical areas. 
Periodicity of Vegetation in Ceylon. 
When one considers the arborescent forms in Ceylon a 
variety of phenomena is exhibited among the endemic and 
indigenous species. Schimper stated that in those parts of 
the tropics where there is a distinct climatic periodicity— 
and Peradeniya is one of these—the vegetation is influenced 
by this, and that plants are likely to show periods of rest 
and activity as in temperate zones. This is only obvious in 
certain species, and the phenomena observed for the differ¬ 
ent species are so complicated that they can be better 
studied in detail in a subsequent section. 
In parts of the tropics where the rainfall is more or less 
evenly distributed throughout the year—as at Buitenzorg— 
periodicity in vegetation is still met with. Schimper 
believed that in districts continually supplied with abundant 
rain there are phases of rest and activity at all times of the 
year in the life-history of the plants. 
In parts of the tropics like Peradeniya there is a definite 
climatic periodicity, and the trees may or may not show 
periodicities in association with this, but before describing 
these we will briefly summarize the conclusions which can 
be drawn from a study of the general vegetation in such a 
district. 
One of the first things to impress a new arrival in Ceylon is 
the absence of any period during which the herbaceous and 
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