4. Dendrocnide urentissima (Gagnepain) Chew, Gard. Bull. Singapore. 21: 207. 1965.
火麻树 huo ma shu
Laportea urentissima Gagnepain, Bull. Soc. Bot. France 75: 3. 1928; Dendrocnide chingiana (Handel-Mazzettii) Chew; Laportea chingiana Handel-Mazzetti.
Trees 3-15 m tall, 8-20 cm d.b.h.; bark whitish gray, lenticels elliptic; leaf scars semiorbicular, conspicuous; upper stem and branchlets velutinous and armed with stinging hairs, soon glabrescent. Stipules caducous, triangular-ovate, ca. 1 cm, leathery, puberulent abaxially; petiole 7-15 cm, velutinous and armed with short stinging hairs; leaf blade dark green, cordate, 15-25 × 12-22 cm, papery, 3-5-veined, lateral veins 5-7 each side, anastomosing before margin, adaxial surface strigose and sparsely armed with short, stinging hairs, abaxial surface velutinous, with red glandular dots, armed with stinging hairs on veins, base cordate, margin entire or inconspicuously serrulate at apex, apex acuminate; cystoliths minutely punctiform, conspicuous adaxially. Inflorescences in subterminal axils of branchlets, long paniculate, shorter than leaves; female inflorescences longer than leaves, to 50 cm, peduncles to 25 cm, densely armed with stinging hairs. Male flowers subsessile, in bud 2 mm; perianth lobes 5, ovate, pubescent; stamens 5; rudimentary ovary obconic, 1 mm. Female flowers 4-6 in a row on slightly fleshy flabellate peduncular receptacle, entirely sessile, ca. 1 mm; perianth lobes 4, unequal, 1 large, ca. 1 mm, 2 medium ca. 0.5 mm, 1 small, ca. 0.3 mm. Ovary ca. 1 mm; stigma ligulate, ca. 3 mm; bracts ca. 0.3 mm. Achene dark reddish, subglobose, oblique, compressed, ca. 3 mm in diam., conspicuously verrucose; persistent perianth forming a minute cupule at base. Fl. Sep-Oct or Jan-Feb, fr. Oct-Dec or Apr-May.
Mixed forests on limestone; 800-1300 m. SW Guangxi, S Yunnan [Vietnam].