IN CEYLON. 423 
whole patch begins to wither and ripen the seed, and then 
dies down. 
Mr. Farr informs me that there is one species, rather rare, 
which flowers and dies down every year, but that S. sexennis, 
Nees ; S. puleherrimus, And. ; S. viscosus, And. ; and S. 
calycinus, Nees, flower and die down with the most perfect 
regularity every twelve years. 
We have therefore a periodicity which cannot be correlated 
with an interval of twelve months, and one which adds 
interest to the observations of Warming, Brandis, and others 
on this subject. 
The arborescent vegetation is similarly striking. The fact 
that the trees do not all become leafless during certain 
months, and the irregularity in the production of new leaves 
and of flowers, impresses one with the great difference 
between the growth of vegetation in the tropics and 
temperate zones. 
The absence of a general time agreement in floral or foliar 
periodicity in Ceylon vegetation at a given place is one of its 
striking characteristics. 
Periodicity of Arborescent Plants in Ceylon. 
There are about 770 endemic species in Ceylon, over 280 
of which are trees. About 17 of our endemic and 78 indi¬ 
genous species pass through a leafless phase at more or less 
regular intervals, showing that only a remarkably low 
proportion of Ceylon trees are deciduous. The number of 
deciduous introduced trees is equal to the number of deci¬ 
duous indigenous and endemic trees put together, a fact 
which superficially considered seems to suggest that the 
Ceylon climate favours deciduous introduced species. 
Ceylon Forest Types . 
The appearance of the forest vegetation in Ceylon at 
various times of the year has not been described, and as many 
opportunities have presented themselves to the writer, an 
