242 FOXWORTHY. 
DIPTEROCARPUS Gjiertn. f. 
Large trees, with long clear boles and rather thin, very resinous and 
scurfy Lark. Leaves usually coriaceous^ but membranaceous in D. affinis 
and in seedlings of D. vernicifluus and other species. Leaves usually 
entire but sometimes retuse or even dentate (young D, gtmidiflorus). 
Stipules ainplexicaul and leaving a pronounced scar encircling the twig. 
Secondary nerves mostly straight^ joined by parallel and reticulate 
tertiary nerves. Tn the bud the two halves of the leaf are folded upon 
each other, and the sections contained between two secondary nerves are 
also folded in half. The folds between two secondary neiTes in most 
species are cloai'ly seen in the mature leaf, and in some cases the tertiary 
nerves show an angle along the line of this fold. Flowers large in 
few-flowered racemes which are sometimes branched. Stamens ^, the 
anthers sometimes twisted. Connective prolonged into a long-pointed 
acunion. Tube of fruiting calyx not adnate to fruit, globose or ovoid, 
smooth or with five ribs or wings, alternating wdth segments, and formed 
by tlie decurrent margins of the segments, two of which develop into 
lai'ge membranaceous or chartaceous wings. 
The pith of a leaf-])earing internode has a large number, up to 100, 
of resin-ducts, which sometimes are arranged in two concentric circles. 
The petiole below the insertion of the blade shows on the under side a 
semacircle of 5-13 ha If -mo on-shaped vascular bundles, each with a resin- 
duct. This semicircle is more or less closed on the upper side by a bar 
of xylem with phloem outside. A central body of vascular bundles 
var}'ing in shape, with 1-8 resin-ducts is present. In most species, there 
are large mucilage-cavities in pith and bark. This is the most distinct 
of our Philippine genei-a. The stipule-scar encircling the stem and the 
large number of resin-ducts in the circumference of the pith are enough 
to separate it even in sterile material. In many cases too, the twngs are 
very' coarse, much more so than in our other genera. 
Dipterocarpus, like Anisoptera, seems to be free from deposits of hard 
resin in the wood, but there is a very abundant flow of a sticky oil on 
freshly cut stumps. This oil is evident in freshly cut wood, and is m 
sufficient quantity to be of coimnercial importance. It is collected by 
chopping into the tree, often half way through the trunk, and leaving 
a big cavity where the oil can collect. The flow of oil is stimulated by 
firing, and sometimes amounts to more than one kilo per day. The oil 
is used for caulking boats and for illuminating pui-poses and it could 
probably be used in the making of varnish. Its chemistry has been 
studied by Clover » and Bacon.^*' It seems to be practically the same 
as the gurjnn balsam of India and the minijaJc brewing of the Malay 
Teninsula. It is reputed to be useful in the treatment of gonorrhoea. 
•This Journal 1 (190G) lUo. '^bid. 4 (1909) A 121. 
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