Dipterocarpus] XVII. DIPTEROCARPACEAE 65 1. DIPTEROCARPUS, Gaertn. f. : Fl. Brit. Ind. i. 295. Tall, regularly shaped trunks, no heartwood. Leaves are renewed at the end of the hot season, when the old leaves fall. Secondary nerves prominent, straight, joined by parallel tertiary nerves. In bud the two halves of the leaf are folded upon each other and the sections between two secondary nerves are also folded in half. Fl. large, pink, in short few-fid. axillary panicles. Receptacle concave, continued into a campanulate or obconical calyx tube with 5 segments, 2 of which are larger. Stamens x, connective prolonged into a long point, anther cells mostly equal. Ovary generally hairy, continued into a conical fleshy stylopodium, style filiform, stigma minute. Tube of fruiting calyx enclosing fruit, but not adnate to it, globose or ovoid, smooth or with 5 ribs or wings, alternating with calyx segments, two of which develop into large longitudinally veined wings. Pericarp thin at the base, thick and fibrous in the upper portion. The cotyledons of the germinating seed remain enclosed in the pericarp and fruiting calyx, being attached to the radicle by long petioles. Species 64. Numerous (up to 100) resin ducts in a leaf-bearing internode near the circumference of the pith. The lateral leaf traces enter the bark at varying levels, generally in the upper half of the internode. Numerous stipular traces in the bark below the node. Frequently large mucilage cavities in pith and cortex. A. Tube of fruiting calyx smooth. 1. D. turbinatus, Gaertn. f. — Syn. D. laevis, Ham.; Roxb. Cor. PL t. 213; Kurz, F. Fl. i. 114. Vera. Gurjun, Chittagong; Kanyin-ni, Burm. Leaves ovate or ovate-lanceolate, blade 5-12 in., petiole rarely more than I the length of blade, secondary nerves 14-18 pair. Varies greatly in regard to the pubescence of young shoots, leaves and inflorescence. Kurz calls the form with glabrous and glossy leaves. D. laevis, that with hoary leaves D. turbinatus. Cachar, Tipperah, Chittagong hills, Burma, Andamans, Malay Peninsula. Fl. April. Fruit May. As a rule not gregarious, but scattered in mixed forest, generally taller than the trees associated with it. North of Bhamo D. laevis is reported to grow gregarious in patches. Yields wood oil. Heartwood reddish-grey, not durable. Closely allied is 2. D. indicus, Bedd. Fl. Sylv. t. 94 (D. turbinatus, Cooke, Bombay Fl. i. 84). Yennemara, Coorg; Ennai. Tam.; Velayani, Mal. Evergreen forest of the Western Ghats from North Kanara southwards. Fl. January-March. Petioles longer, 1/2 to 1/4 the length of blade, and secondary nerves less numerous, 10-15 pair. 3. D. obtusifolius, Teysm. : Kurz, F. Fl. i. 115. young shoots, petioles and inflorescence] densely clothed with long pale lawny hair. Leaves broadly ovate, obtuse, to 9 in. long, pubescent above, softly tomentose beneath, secondary nerves 12-14 pair. Fl. showy, pink, shortly pedicellate on short axillary racemes. Fruit 1 1/4 in. diam. Throughout the Eastern Peninsula, 20° N. Lat. its northern limit. In Cochinchina and Cambodia very common and gregarious. Ascends to 3,000 ft. in Pegu and Martaban ; at higher elevations gregarious, forming forests similar to those of D, tuberculatus. D. vestitus, Wall., Tavoy, very similar and probably not specifically distinct. 4. D. pilosus, Roxb. ; Kurz F. Fl. i. 115. — Syn. D. Baudii, Korthals. Young shoots, stipules and petioles densely clothed with tawny fascicled hairs. Leaves elliptic-oblong, shortly acuminate, 8-18 in. long, ciliate at the edges, hairy beneath, secondary nerves 20-25 pair. Fruiting calyx glabrous, ovoid. 2 in. long, wings to 9 in. Fruit densely pubescent. Damp forests in the upper part of the Assam valley, Chittagong hills, Aracan, Lower Burma, Andamans(?). Fruit April, Sumatra (gregarious, Korthals), Bangka, Yields a semifluid resin.