Rubia

Scrambling, creeping or climbing perennial herbs, somewhat woody near base; roots somewhat woody, reddish (yielding a red dye); stems branched, 4-angled, +/- brittle, mostly beset with recurved prickles. Leaves and stipules similar, in whorls of 4-8(-12), petiolate; blades cordate or broadly ovate, ovate-lanceolate to linear, rounded to +/- cordate at base or narrowed to base, with 1-5(-7) prominent veins. Flowers in axillary and/or terminal cymes, bisexual, (4)5(6)-merous. Calyx with lobes obsolete. Corolla rotate to subcampanulate, greenish, yellowish green to yellow; lobes +/- triangular, (long-)acuminate. Stamens: anthers exserted. Ovary crowned by a minute disc; 2-locular, 1 ovule in each chamber arising on septum; style branches 2, joined below; stigmas capitate. Fruit fleshy, glabrous, consisting of 2 round mericarps, each with a single seed, round on dorsal side, plane to convex on ventral side; one mericarp often aborted. x = 11 (B-chromosomes, high polyploidy).