Description from Flora of China
Vines, herbaceous, or ± climbing herbs; stems to perhaps 1.5 m, quadrangular to 4-ridged, glabrous, ribs aculeolate. Leaves in whorls of 4; petiole 3-12 cm, aculeolate, often pulvinate and strongly bent at base of blade; blade drying papery, grayish brown, linear to narrowly lanceolate, 3-9 × 0.5-1 cm, both surfaces glabrous, smooth or sparsely scaberulous, base obtuse to rounded, margin flat and smooth to denticulate, apex acute to acuminate; principal veins 3, palmate. Inflorescences thyrsoid, paniculate, with terminal and axillary, few- to many-flowered cymes; axes glabrous, aculeolate; bracts linear-lanceolate, 0.5-3 mm; pedicels 3-4 mm. Ovary ca. 0.5 mm, scaberulous. Corolla green, rotate, glabrous; fused basal part ca. 0.5 mm; lobes lanceolate-triangular, ca. 1 mm, cuspidate. Fruit apparently black, 5-6 mm. Fl. Jun-Jul, fr. Sep.
This species belongs to Rubia ser. Cordifoliae and has been well illustrated in H. S. Lo (in FRPS 71(2): 312, t. 70, f. 7-12. 1999). The above description is based in part on provisionally identified specimens, some of them from Guangdong. Affinities may exist with R. alata and its transitional forms with R. cordifolia agg. (see additional comments under these species).
● Moist valleys; ca. 2000 m. Guangdong, Sichuan (Jiulong), ?Yunnan.