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 live 
sepals are developed into long wings much larger than the fruit. 
In Dipterocarfius, A nisoptera, 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 lorms a cup at the 
base of the fruit, Pretinodendton and Pachy nocarpus, 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 method of growth 
in any tree in the Malay Peninsula. In Assam, Burrnah and 
Cochin-China however, there are several Dipterocarps which habi- 
tually form forests to the exclusion of other trees notably the Sal 
tree {Shorea robnsta). Dipterocarps, as a rule, only flower when 
they have attained a great size. Pachynocarpus, Isoptera and 
Pentacme however often flower when 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 find 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 
