Dipterocarpus retusus Blume

Dipterocarpus species are trees. Bark grayish or orange brown or sometimes pinkish brown, bole straight, base of the trunk buttressed or dome shaped, flaked in patches, densely lenticellate and with aromatic white resin, branchlets with tubercular dots and subulate scales. Leaves simple, alternate, lanceolate-ovate to oblanceolate-elliptic, base obtuse to cuneate, margins entire usually sinuate towards the apex, apex obtuse to acute, plicately folded in bud, leathery, coriaceous, midrib impressed above and prominent beneath, lateral veins straight, curved near margins, tertiary veins scalariform, petiole stout, geniculate, stipules large encircling twigs near terminal buds, hastate to lorate, succulent, caducous, scars annular. Inflorescence axillary or terminal, somewhat irregular cymes or panicles. Flowers bisexual, large, fragrant, pink or white, pedicel short, calyx 5 lobed, tubular with short valvate lobes, 2 longer, spathulate-oblong, triveined, 3 lobes short, forming a crown round apex, petals 5, narrow oblong, large, white, with dark red or pink strip near centre. Stamens 15 or more, adnate persistent, filaments unequal base connate, broad tapering and filiform near yellow anthers, pollen sacs 4, connective short, filiform. Ovary enclosed inside calyx tube, narrow ovoid-conical, puberulent, style filiform, glabrous, stigma dilated. Fruit large, nutlike, enclosed in calyx tube with 2 accrescent lobes like wings. Seeds adnate at the base, cotyledons large, unequal.

Tree

Dipterocarpus species flowers are complete, bisexual, i.e., with functional male (androecium) and female (gynoecium), including stamens, carpels and ovary. Pollination is entomophilous i.e., by insects, or cleistogamy i.e., by self or allogamy i.e., by cross pollination. Flowering/Fruiting: June—November/August—March.

Seeds may be dispersed by autochory i.e., self dispersal, anemochory i.e., wind dispersal, zoochory i.e., dispersal by birds or animals, anthropochory i.e., dispersal by humans.

Evergreen trees, about 30-50 m tall, trunk about 3-5 m in girth. Bark smooth, pale bluish grey, pale reddish brown inside, bole straight, raised tubercles at trunk base and with aromatic white resin, base of the trunk buttressed, branchlets with tubercular dots, densely buff puberulent or glabrous. Leaves simple, alternate, elliptic to obovate-elliptic, about 14-25 x 9-15 cm across, base obtuse to cuneate, margins slightly undulate, apex abruptly short acuminate or cuspidate, plicately folded in bud, membranous, coriaceous, midrib impressed above and prominent beneath, lateral veins straight, 12-25, curved near margins, tertiary veins transverse, petiole buff pubescent or sparsely pilose, about 4-5 cm long, stipules encircling twigs near terminal buds, glabrous or punctuate inside, densely buff pilose outside with fascicled hairs, caducous, about 7.5-12.5 cm long, scars annular. Inflorescence axillary, somewhat irregular spikes or cymes, simple or branched, about 2-6 flowered, peduncles about 5-8 cm long, densely buff pubescent. Flowers bisexual, large, fragrant, pedicel slender, calyx 5 lobed, tubular with short valvate lobes, silkly pubescent inside, velvety buff puberulous outside, 2 longer, linear oblong, strap shaped, about 2-2.5 x 0.3-0.5 cm across, 3 lobes shorter, deltoid-triangular, forming a crown round apex, about 2 mm long, petals 5, narrow oblong-oblanceolate, membranous, faintly veined. Stamens 30, adnate persistent, during anthesis longer than the style, filaments unequal base connate, yellow anthers, linear lanceolate, about 6-8 mm long, pollen sacs 4, connective appendage, filiform, about 4 mm long. Ovary enclosed inside calyx tube, narrow ovoid-conical, about 6 x 4 mm across, 3 locular, 2 ovules per locule, densely tomentose, style filiform, base pilose apex glabrous, about 1.5 cm long, stigma dilated. Fruit nut-like, globose, about 1.5-2.5 cm long, base 5 winged, enclosed in calyx tube with 2 accrescent lobes like wings, linear ovate, stellate tomentose, about 15-28 x 3.8-5 cm across, trinerved. Seeds adnate at the base.

Dipterocarpus species are susceptible to various insect pests, virus and fungi, affecting leaves, fruits and roots.

Tropical wet evergreen forests, altitude up to 1000 m.

Rain forests, moist evergreen and sometimes semi-deciduous forest

Vulnerable (IUCN).

Wood is used to making plywood, railway sleepers and tea chests.