Vasilis Teodoridis:
Fagaceae | Castanopsis
26. Castanopsis tonkinensis Seemen; Bot. Jahrb. Syst. 23 (Beibl. 57): 55. 1897.
??? gong sun zhui
Trees 10-20 m tall. Branches glabrous. Petiole 1-2 cm; leaf blade lanceolate; 6-13 x 1.5-4 cm; membranous; abaxially greenish and sparsely covered with reddish brown; small; lamellate; waxy scalelike trichomes when young; glabrous at maturity; adaxially deep green; base narrowly cuneate; decurrent on petiole; and symmetric or slightly oblique; margin entire; apex caudate to sometimes shortly acute; midvein adaxially somewhat impressed and villous but glabrescent; secondary veins 9-13 on each side of midvein. Female inflorescence ca. 20 cm. Cupule broadly ellipsoid; ovoid; or rarely subglobose; 2-3 cm in diam.; dark brownish black when dry; outside glabrescent; wall 0.5-1 mm thick; bracts spinelike; rarely entirely covering cupule; 6-10 mm; glabrescent. Nut 1 per cupule; narrowly conical to broadly ellipsoid; 0.9-1.2 cm in diam.; densely brown pilose; scar basal; 8-9 mm in diam. Fl. May-Jun; fr. Sep-Oct of following year.
Broad-leaved evergreen forests; below 2000 m. Guangdong; SW Guangxi; Hainan; SE Yunnan [NE Vietnam]
Most Chinese collections are var. tonkinensis; but some specimens from Guangxi and SE Yunnan may be var. laocaiensis Luong; which has broader and thicker leaf blades; and bracts of cupules thicker and shorter than those of var. tonkinensis.