Description from Flora of China
Trees, lofty, emergent, with grayish brown to orange flaky, prominently lenticellate bark and aromatic oily white resin, with stout buttresses. Stipules large, enclosing terminal bud, finally caducous and leaving an annular scar; leaf blade leathery, plicate in bud and ± corrugate when opened; lateral veins pinnate, straight; tertiary veins subscalariform, conspicuous, margin entire or sinuate-crenate. Raceme 3-9-flowered, hardly branched. Flowers large, sweetly scented. Calyx with urceolate or cup-shaped free basal tube; sepals valvate, unequal. Petals white or with a reddish median stripe, pubescent or stellate pubescent especially on parts exposed in bud. Anthers yellow, linear, equivalved; connective appendages aristate or filiform. Ovary narrowly ovoid, pubescent; style filiform; stigma slightly dilated. Fruit nutlike, enclosed in accrescent calyx tube; winglike calyx lobes 2, erect. Seed adnate to base of pericarp; cotyledons large, thick, unequal; radicle inconspicuous.
Dipterocarpus gracilis Blume, which was reported in FRPS (50(2): 114. 1990), is not found in China. It differs in the smaller size of all parts and rufous scabrous tomentum. Its nearest localities are in N Thailand, India (Andaman Islands), and SE Bangladesh.
About 70 species: Cambodia, China, India, W Indonesia, Laos, Malaysia, Myanmar, Philippines, Sri Lanka, Thailand, Vietnam; two species (one introduced) in China.