Dipterocarpus alatus Roxb. & G. Don

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.

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: January—March/April—June.

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 40-80 m tall, about 3-7 m in girth. Bark pale grayish, pale yellow inside, bole straight, base of the trunk buttressed, flaked in patches, densely lenticellate and with aromatic white resin, branchlets with tubercular dots and subulate scales. Leaves simple, alternate, ovate to ovate-elliptic, about 8-22 x 5-12 cm across, base obtuse to cuneate, margins entire, apex acute short acuminate, plicately folded in bud, leathery, coriaceous, midrib impressed above and prominent beneath, lateral veins straight, 10-18, curved near margins, tertiary veins scalariform, petiole stout, softly pubescent, about 2.5-4 cm long, stipules encircling twigs near terminal buds, stellate tomentose, succulent, caducous, about 5-8 cm long, scars annular. Inflorescence axillary, somewhat irregular cymes, simple or branched, about 3-7 flowered, lower flower with shorter pedicel. Flowers bisexual, large, fragrant, yellowish white or white, pedicel about 3-3.5 cm long, calyx 5 lobed, tubular with short valvate lobes, 2 longer, spathulate-oblong, triveined, 3 lobes short, forming a crown round apex, about 1-1.5 cm long, petals 5, narrow oblong, large, white, pale yellow, about 3 mm long. Stamens 30-33, adnate persistent, filaments unequal base connate, broad tapering and filiform near yellow anthers, about 4 mm long, pollen sacs 4, connective short, filiform. Ovary enclosed inside calyx tube, narrow ovoid-conical, densely tomentose, style filiform, base pilose apex glabrous, 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, glaucous, about 10-12.5 x 2.5 cm across, trinerved. Seeds adnate at the base, cotyledons large, unequal.

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

Evergreen and semi evergreen forests of low elevation.

Endangered (IUCN).

Used in Ayurvedic and Tibetian medicine, resin used for making plasters, bark decoction used for rheumatic problems, wood used in construction work, making chests etc.