Shrubs or small trees, up to 5 m tall, to 15 cm d.b.h. Branchlets yellow-white initially but soon grayed, slender, glabrous, warty, lenticellate, with distinctive leaf scars; young ones ± angled; innovation covered with long and finely appressed hairs. Leaves alternate; petiole brown, (0.5-)1-2.3 cm, concave-convex, glabrous; leaf blade glaucous abaxially when young but nearly concolorous on both surfaces when mature, shiny adaxially, suboblanceolate to oblanceolate-elliptic, 3.5-9 × 1.5-4 cm, thinly leathery, glabrous on both surfaces, midrib elevated abaxially, impressed on its lower part at least adaxially, lateral veins (7 or)8-10 pairs, oblique-patent, arcuately interconnected near leaf margin, veins and veinlets conspicuous and foveolate on both surfaces, base attenuate and acute, apex shortly acuminate or obtuse. Panicle axillary, up to 2.5 cm before anthesis, very slender, glabrous, few flowered, few branched or nearly unbranched; peduncle slender; bracts and bracteoles subulate, deciduous. Pedicels slender, up to 5 mm. Flowers small, glabrous, up to 1.5 mm. Perianth tube broadly obconical, 0.5-0.8 mm; perianth lobes 6, subequal, broadly ovate, thin, 1.2-1.5 × 1.2-1.3 mm. Fertile stamens 9, densely golden villous, ca. 0.8 mm (of 1st and 2nd whorls) or ca. 0.7 mm (of 3rd whorl); filaments of 3rd whorl each with 2 suborbicular-cordate glands at base, those of 1st and 2nd whorls glandless; anthers of 1st and 2nd whorls broadly ovoid, with 2 introrse cells, those of 3rd whorl ovoid-square, truncate at apex, with extrorse cells. Staminodes deltoid-conical, stalked, including stalk ca. 0.6 mm; stalk densely golden yellow villous. Ovary ovoid, including style ca. 1.2 mm; style slightly slender; stigma small and subpeltate. Fruit ovoid, ca. 1.2 mm; fruit stalk slightly thickened, ca. as long as fruit. Fl. Apr-Jun, fr. Jul-Oct.

Records of Dehaasia cairocan (S. Vidal) C. K. Allen (Beilschmiedia cairocan S. Vidal) from China (e.g., in Fl. Hainan. 1: 275. 1964) are referable to D. hainanensis.

● Dense forests, thickets. Hainan.