428 WRIGHT : FOLIAR PERIODICITY 
describing the vegetation of the Campos of Minas-Geraes in 
Brazil, states that the majority of the leaves remain on the 
trees from twelve to fourteen months, and usually fora longer 
period in the forests than on the prairies. Some trees, 
according to Warming, retain their foliage for twenty-four 
months and even longer. Such cases are comparatively rare 
in Ceylon, but they prove that an annual defoliation is not 
universal with deciduous trees, and that a change of leaf at 
periods coinciding with our year of twelve months isi not 
necessary for every species. 
Once per year .—The majority of the observed species do 
not show a long or irregular interval between successive 
periods of defoliation. Nearly all of them pass through 
their leafless state once each year, and I need only mention 
Bombax malabaricum, Spondias mangifera, Careya arborea, 
Gmelina arborea, Terminalia belerica, Ficus Arnottiana, 
Oroxylum indicum, Bridelia retusa, Canarium zeylanicum, 
&e., as examples of this group. 
Twice per year .—There is only one species which under¬ 
goes a change of leaf twice each year, this being Terminalia 
Catappa; the change of leaf in the Peradeniya district 
usually takes place in February to March and August to 
September. The tree is a native of Malaya, but is naturalized 
in the low-country of Ceylon, where it is known as the 
“kottamba” of the Sinhalese and the “ country almond” of 
the English. 
There are a few other species which are completely 
defoliated once a year, but which pass through the leafless 
stage twice during certain years. Examples may be seen in 
a tree of Ficus asperrima, at Peradenija, which, though 
usually defoliated in March only, was defoliated in March 
and October in 1903. Similarly with some specimens of 
Couroupita guianensis. 
Still another combination of foliar activity is seen in Ficus 
Trimeni, which appears to be subject to complete or partial 
defoliation in December and January, and to a partial leaf- 
fall in June and July of certain years. A description of the 
