Description from Flora of China
Nauclea sinensis Oliver, Hooker’s Icon. Pl. 20: t. 1956. 1891; Uncaria membranifolia F. C. How.
Lianas, height unknown. Young stems slender, quadrangular, glabrous. Petiole 6-10 mm, glabrous; leaf blade drying thinly papery, elliptic to ovate, 9-14 × 5-8.5 cm, both surfaces sparsely puberulent to glabrous, base obtuse to rounded, apex acuminate; secondary veins 6-8 pairs, without domatia; stipules often persistent, broadly triangular, ovate, or orbicular, 3-10 mm, glabrous, rounded to truncate or sometimes shallowly emarginate. Inflorescences axillary, heads solitary or sometimes in terminal groups of 3-5, glabrous; peduncles 3-7 cm, rather slender; bracts 2-3 mm; flowering heads 10-15 mm in diam. across calyces, ca. 30 mm in diam. across corollas; bracteoles linear or subspatulate, 2-3 mm. Flowers subsessile. Calyx with hypanthium portion ca. 2 mm, densely strigose to strigillose; limb deeply lobed, densely strigillose; lobes linear-oblong, 1-1.5 mm, obtuse to rounded. Corolla color unknown, salverform; tube 7-8 mm, outside glabrous; lobes ligulate to triangular, ca. 2 mm, outside puberulent, acute to obtuse. Fruiting head 20-30 mm in diam. Fruit sessile, ellipsoid, 8-10 mm, strigillose to strigose; seeds not seen. Fl. and fr. Jun-Oct.
This species was illustrated by How (Sunyatsenia 6: 254, f. 30. 1946, as Uncaria membranifolia).
● Sparse forests or wet secondary forests at middle elevations; 900-1100 m. Gansu, Guangxi, Guizhou, Hubei, Hunan, Shaanxi, Sichuan, Yunnan.