Herbs, climbing or scrambling; stems 0.5-1.5 m, quadrangular, densely hirtellous or hispidulous with trichomes usually hooked, angles aculeolate. Leaves in whorls of 4; petiole 0.2-1.5 cm, hirtellous; blade drying rather thickly papery, lanceolate to ovate, 0.8-2.5(-3.5) × 0.3-0.8(-1.5) cm, adaxially densely scaberulous and sometimes also hooked hirtellous, abaxially moderately to densely hirtellous, base rounded to usually cordulate, margin thinly revolute and aculeolate, apex obtuse to shortly acute; principal veins 3(or 5), palmate. Inflorescences thyrsoid, paniculate, with terminal and axillary, several- to many-flowered cymes; axes hirtellous or pilosulous, aculeolate; bracteoles lanceolate to narrowly elliptic, 2-5 mm; pedicels 0.5-3(-8) mm. Ovary 0.8-1 mm, smooth. Corolla white or yellow, cup-shaped, outside sparsely to densely hirtellous, fused basal part 0.8-1 mm; lobes triangular-ovate, 1.8-2 mm, caudate-acuminate. Mericarp berry 3-3.5 mm in diam., color unknown. Fl. Jul-Sep, fr. Sep-Nov.

Rubia oncotricha, apparently endemic to SW China, is aberrant by its mostly hooked indumentum (H. S. Lo in FRPS 71(2): 300, t. 65, f. 10-14. 1999). Nevertheless, it clearly belongs to R. ser. Cordifoliae (see additional comments under R. cordifolia).

● Forest margins, sparse forests, and grasslands on mountain slopes; 500-3200 m. Guangxi, Guizhou, Sichuan, Yunnan.