53 



The plants included in this order are all trees of large often vast 

 size, attaining sometimes a height of 200 feet, with a diameter of 

 6 feet. They have a bare straight stem 80 feet or so to the first 

 branch, often buttressed at the base, but as a rule the buttresses 

 are not so large as in many other trees. The leaves vary much in 

 size and form but are seldom large, usually coriacious, and the leaf - 

 stalk is almost invariably thickened below the blade of the leaf, 

 and the branchlets show especially when dry a raised line running 

 up along one side to join the base of the leaf-stalk, (the lateral 

 leaf trace. Brandis Enumeration of the Dipterocarpeae. Jour. 

 Lin. Soc.) The flowers are arranged in racemes or panicles and 

 are recognisable by their twisted petals, pink, white or yellow, 

 usually very sweet scented. They are largest in the genus Diptero- 

 carpus, and quite small in Shorea and Hopea. The fruit gives the 

 simplest and best character for distinguishing the genera and 

 species. The fruit consists of a single seeded round nut, sur- 

 rounded by the enlarged calyx. The sepals of which are usually 

 developed into long narrow wings by the aid of which the ripe fruit 

 is drifted away in the wind and so spread over the forests. In 

 Dryobalanops, Parashorea and one section of Vatica all the five 

 sepals are developed into long wings much larger than the fruit. 

 In Dipterocarpus , Anisoptera, Hopea, Cotylelobium, and some 

 Vaticas, only two are developed. In Shorea and Pentacme, three. 

 In Isoptera the sepals are rounded and spreading, but shorter than 

 the fruit. In Balanocarpus (Chengei) the calyx forms a cup at the 

 base of the fruit, Pretinodendton and Pachynocarpus , have rough 

 brown fruits without any wings. 



The Dipterocarps usually grow scattered through the jungles. 

 The Camphor tree being the only exception. This latter in the 

 only two places in the Peninsula where it is known to occur forms 

 forests consisting exclusively of itself. It is said by Korthals to 

 do the same in Sumatra, but it is a most unusual metho 1 of growth 

 in any tree in the Malay Peninsula. In Assam, Burmah and 

 Cochin-China however, there are several Dipterocarps which habi- 

 tually form forests to the exclusion of other trees notably the Sal 

 tree {Shorea robusta). Dipterocarps, as a rule, only flower when 

 they have attained a great size. Pachvnocarpus, Isoptera and 

 Pentacme however often flower wh^n comparatively small trees. 



Only a few of the Dipterocarps flower annually when they are 

 old enough to flower. Many species of Dipterocarpus flower every 

 year, or almost every year, as does Pachynocarpus and one or two 

 others. But, as a rule, the Shoreas and Hopeas flower only once 

 in six years, when the weather becomes very dry. This makes the 

 propagation of these trees somewhat troublesome. As for five 

 years out of six no seed is procurable. The seed is produced in 

 great quantities when the trees do fruit and usually germinate 

 readily though a very large proportion of those that first fall are 

 barren. Indeed in some Dipterocarpi it is common to tind the 

 seed in the ovary replaced by wood-oil. The growth of the tree 

 is very slow. But it is difficult to form any very accurate idea of 

 the rapidity of growth as at present there are no records of planted 



