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WRIGHT : FOLIAR PERIODICITY 
Nature of defoliation and foliar renewal ,—The species 
may be classified into three groups. 
The first group comprises those species which become 
absolutely leafless, typical examples being Allæanthus 
zeylanicus, Thw., Canarium zeylanicum, BL, Canthium 
macrocarpum, Thw., Holarrhena mitis, Br., Pericopsis 
Mooniana, Thw., Terminalia parviflora, Thw. 
These species may undergo complete defoliation before any 
new leaf-buds appear, though this behaviour is rarely as 
conspicuous as in indigenous forms. The actual length of 
time during which they are leafless is very limited, and may 
be, for particular species, from 31st January to 17th Feb¬ 
ruary, 7th to 20th March, and 29th August to 4th September. 
The actual period required for a complete renewal of foliage 
is of course much longer. With trees of Canarium zeylanicum 
the leaves may commence to fall on the 3rd February and 
continue to do so until the 7th or 12th March, when the tree 
is quite leafless ; new leaf-buds appear from the 20th to the 
28th March and the trees regain a complete outfit of mature 
leaves by the 11th April. Similarly for trees of Allæanthus 
zeylanicus, the period extends from 6th January to the 17th 
March, and with Terminalia parviflora from 10th February 
to 29th March. One tree of Holarrhena mitis effected com¬ 
plete defoliation and renewal within the month of March 
in 1902. 
The phenomenon of foliar renewal is often so quick that 
the change of leaf on a tree of a particular species may be 
unnoticed. 
The second class comprises those plants which though they 
may undergo a complete change of foliage within one or two 
weeks, are never absolutely leafless, on account of the pro¬ 
duction of new leaves on one part of the tree before al] the 
old leaves have fallen. 
Under certain circumstances trees of Terminalia parviflora 
and Canarium zeylanicum may behave in this way, but since 
they often become leafless they have been included in the 
