Description from Flora of China
Nauclea rhynchophylla Miquel, Ann. Mus. Bot. Lugduno-Batavi 3: 108. 1867; Ourouparia rhynchophylla (Miquel) Matsumura; Uncaria rhynchophylla var. koutong Yamazaki.
Lianas, height unknown. Young stems slender, weakly to markedly quadrangular, glabrous, sometimes glaucous. Petiole 5-15 mm, glabrous; leaf blade drying papery and often red-brown or dark red, elliptic, lanceolate, or elliptic-oblong, 5-12 × 3-7 cm, glabrous on both surfaces, often glaucous abaxially, base cuneate, obtuse, or rounded, apex acute to usually acuminate; secondary veins 4-8 pairs, sometimes with pilosulous domatia; stipules often deciduous, lanceolate to ovate, 4-15 mm, 2-lobed for up to 4/5, glabrous, lobes linear to triangular-lanceolate or ovate, acute to acuminate. Inflorescences axillary and terminal, solitary or usually in terminal groups of 7-11, glabrous; peduncles 1.5-5 cm, simple; bracts 1-4 mm; flowering heads 4-8 mm in diam. across calyces, 12-15 mm in diam. across corollas; bracteoles linear or linear-spatulate, ca. 2 mm. Flowers sessile or subsessile. Calyx with hypanthium portion obconic, ca. 1 mm, densely strigillose to strigose; limb densely strigillose, ca. 1 mm, lobed for 1/2 or more; lobes triangular to spatulate, acute to obtuse. Corolla color unknown, salverform, outside puberulent to glabrous; tube 5.5-6 mm; lobes ovate, 1.5-2 mm, rounded to obtuse. Fruiting head 10-20 mm in diam. Fruit sessile or subsessile, obovoid to fusiform, 5-7 mm, strigillose to strigose; seeds 2-3 mm. Fl. and fr. May-Dec.
Ridsdale (Blumea 24: 93. 1978) included Uncaria rhynchophylloides as a synonym of U. rhynchophylla; however, these do appear to be distinct.
Sparse forests or thickets at streamsides in valleys; near sea level to 1000 m. Fujian, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangxi, Yunnan, Zhejiang [Japan].