Perennial herb, branched at the base, with several subprostrate hairy stems, up to 60 cm. long, which are erect at their apices. Most parts of the plant smell quite strongly of carbon disulphide when crushed or extracted with alcohol. Leaf-blades ovate to ovate-lanceolate, 3–8 cm. long, 1.5–2.9 cm. wide, acute at the apex, cuneate at the base, pubescent on both surfaces; petioles 0.4–1.2 cm. long; stipules with 5–7 subequal segments 2–5.5(–9) mm. long, from a base 2–4 mm. long. Inflorescences axillary, the flowers at first arranged in compact heads, but later extending and becoming spikes up to 5 cm. long; peduncles 0.8–7 cm. long; pedicels 0.3 mm. long. Flowers lilac, white, pinkish red or purple, dimorphic. Calyx-tube ovoid, 1–1.5 mm. long, 0.75–1 mm. wide, glabrescent; lobes 5, 1 foliaceous, 4–6 mm. long, 1–2 mm. wide, ciliate, the rest minute, hairy, ± 0.5 mm. long, Corolla-tube 5–9.5 mm. long, ± 1 mm. wide at the base, 1.5–2 mm. wide at the apex, pubescent outside, hairy inside the throat; lobes 5–6, oblong-lanceolate, (1.5–)2.5–3 mm. long, ± 1–1.5 mm. wide, glabrous inside, pubescent outside, the apices somewhat inflexed. Style in long-styled flowers exserted 1–3 mm.; stigma bifid, the lobes filiform, 1.5 mm. long, Fruit ovoid, brownish black, 2.5 mm. long, 2.5–3.5 mm. across, somewhat narrowed at the apex, divided into 2 indehiscent cocci between which there are numerous rhaphides. Seeds brown, elliptic, thin, 1.2 mm. long, 0.5 mm. wide.
