北越钩藤 bei yue gou teng

Uncaria tonkinensis Haviland.

Lianas, climbing to 25 m tall. Young stems quadrate, sparsely to densely, usually ferruginous tomentulose or -hirtellous. Petiole 3-6 mm, hirtellous to strigose; leaf blade drying papery, elliptic, lanceolate, elliptic-lanceolate, or ovate-lanceolate, 6-10 × 2.5-4 cm, adaxially rather sparsely but evenly puberulent to strigillose on lamina and densely tomentulose on costa, abaxially moderately to densely hirsute or strigose with trichomes produced mostly along veins, base rounded, apex acuminate or caudate; secondary veins 6-8 pairs, usually with well-developed pilosulous domatia; stipules generally deciduous, deeply 2-lobed, lobes narrowly triangular, 4-5 mm, acute. Inflorescences axillary and sometimes also terminal, densely hirtellous to strigose; peduncles simple, 2.5-3 cm, at articulation with narrowly triangular bracts 2-3 mm; flowering heads 7-10 mm in diam. across calyces, 25-30 mm in diam. across corollas; bracteoles apparently absent. Flowers sessile. Calyx with hypanthium portion obconic, ca. 1.2 mm; limb deeply lobed; lobes linear to narrowly triangular, 0.75-1 mm, densely pilosulous, acute. Corolla yellow [to pale green], outside densely strigose to strigillose; tube 5-8.5 mm; lobes ligulate to elliptic-oblong, ca. 1.25 mm, obtuse to rounded. Fruiting heads 12-20 mm in diam. Fruit sessile, obovoid, ca. 4 × 2 mm, strigose to pilosulous; seeds 2-3 mm. Fl. Apr, May.

Evergreen to seasonal forests; 200-600 m. Guangxi, Yunnan [Bangladesh, Cambodia, India, Indonesia, Laos, Malaysia, Myanmar, Thailand, Vietnam].

H. H. Hsue and H. Wu (in FRPS 71(1): 258. 1999) described the leaves as up to 5.5 cm wide, but this has not been seen on specimens studied nor reported by other authors. Ridsdale (Blumea 24: 95. 1978) reported this species from Guangdong and Hainan but without vouchers. The separation here of Uncaria homomalla and U. scandens follows previous Chinese authors, but the separation of these species (or possibly the application of these names to the Chinese plants) needs further study. Ridsdale (loc. cit.) separated U. homomalla from U. scandens based on the size of the flowering heads and leaves; however, Chinese specimens included previously in U. scandens (e.g., Henry 11868, MO!) have flowering heads and leaves similar in size to those of U. homomalla.