ON THE DIPTEROCARPACEZ, 9 
reader to the aceount of the Sumatra Camphor by De Vriese in 
Kew Journ. Bot. iv. pp. 88, 68 (1852), and in regard to Diptero- 
carpus, Shorea, and other genera, to what I have said in Engler’s 
Nat. Pflanzenfam. iii. 6. pp. 245, 257, 259, 266, &c., and ina 
paper of mine published in the ‘ Pharmaceutical Journal,’ vol. liv. 
p. 497. 
Most Dipterocarps are evergreen, the old leaves falling soon 
after the young foliage has developed. In some species, how- 
ever, the duration of the leaves is a little under 12 months. 
Thus the Sal tree is generally leafless during a week or two of 
the hot season, before the young leaves come out. This, how- 
ever, varies according to locality and the peculiarities of the 
season. 
Dipterocarps as a rule are large trees with tall branchless 
stems, which do not flower and seed until they have attained a 
large size and a great age. There are, however, exceptions. 
Many species of Vatica are shrubs or small trees, flowering at an 
early age. A well-known instance is Vatica lanceafolia, Blume, of 
Assam and Cachar. This and similar species are readily gathered 
in flower and fruit. The species of Pachynocarpus and Isoptera 
borneensis, Scheff., grow into large trees; but according to 
information kindly communicated to me by Mr. Ridley, they 
flower and seed at an early age. The same I have noticed in 
Burma in the case of two large trees, Pentacme suavis, A. DC., 
and Shorea obtusa, Wall. On laterite or dry hills, where they are 
associated with Dipterocarpus tuberculatus, small (not always 
aged) specimens of these trees are often found in flower and 
seed. 
As a rule Dipterocarps flower and seed annually, unusual 
seasons excepted. Mr. Ridley, who has devoted attention to this 
subject in the Malay Peninsula, informs me that Dipterocarpus 
cornutus, Dyer, grandiflorus, Blanco, crinitus, Dyer, Vatica 
Ridleyana, Brandis, and Pachynocarpus Wallichii, King, flower 
regularly each year, although any given tree may occasionally 
omit a year or more, even if adult. Mr. Ridley also states that 
every sixth year the weather becomes unusually dry, especially 
during the first half of the year, and that then many species of 
the order produce flowers and seed. The years 1888 and 1894, 
he states were such years, and in those years, among others, 
the following species were found in flower and seed :—Hopea 
intermedia, King, Mengarawan, Miq., Shorea leprosula, Miq., 
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