Description from Flora of China
Shorea assamica Dyer subsp. yingjiangensis Y. K. Yang & J. K. Wu; S. siamensis Miquel var. borealis Y. K. Yang & J. K. Wu.
Trees evergreen, emergent, to 50 m tall, with aromatic white resin smears. Bark dark brown or grayish brown, irregularly exfoliating in scales; inner bark laminated; wood pale, not hard. Branchlets densely grayish yellow tomentose, orbicular lenticellate. Stipules oblong or falcate-ovate, ca. 2 cm, longitudinally 10- or 11-veined, densely grayish yellow tomentose, persistent on juveniles; petiole ca. 1 cm, densely yellow tomentose; leaf blade ovate-elliptic, 6-12 × 3-6 cm, thinly leathery, midvein raised abaxially and conspicuously impressed adaxially, lateral veins 12-19 pairs, pinnate, slender, tertiary veins loosely scalariform and conspicuous, abaxially stellate pubescent, adaxially tomentose along midvein, base rounded or slightly cordate, margin entire, apex acuminate. Flowers in axillary or terminal cymose panicles; bracts caducous. Sepals: outer 3 elliptic and ca. 8 mm, inner 2 lanceolate and ca. 6 mm, all grayish yellow tomentose. Petals yellowish white, contorted, narrowly oblong, longitudinally 11-veined, appressed tomentose outside. Stamens 15; anthers ellipsoid, glabrous; connective appendages filiform, ca. 3 mm glabrous. Ovary ovoid, sparsely pubescent; nut to 1.5 × 1.5 cm; style narrowly cylindric; stigma 3-lobed. Sepal lobes winglike; long wings linear-oblong, 8-10 × ca. 1.5 cm, longitudinally 10-14-veined, short wings linear-lanceolate, 3-5 cm; all tomentellate. Fl. Jun-Jul, fr. Dec-Jan of following year.
This is a rare species in China, threatened by habitat loss. Shorea assamica subsp. globifera (Ridley) Symington accounts for the extra-Chinese distribution.
Tropical valley forests; below 1000 m. SE Xizang, W Yunnan [India, Indonesia (Sumatra), Malaysia, Myanmar, Philippines, Thailand].