Annual herb up to 100(–120) cm tall, sometimes with woody rootstock, with prostrate, ascending or erect, pubescent stems. Leaves opposite or nearly opposite, simple; stipules absent; petiole up to 6 cm long in lower leaves, very short in upper leaves; blade lanceolate-deltate to ovate-triangular or narrowly ovate, 1.5–8 cm × 0.5–4.5 cm, truncate, broadly cuneate or slightly hastate at base, acute at apex, usually coarsely toothed at least toward base, pubescent and densely glandular below, sparsely so above, palmately veined at base. Flowers solitary in leaf axils, bisexual, zygomorphic, 5-merous; pedicel 3–8 mm long; calyx with narrowly triangular lobes up to 7 mm long, connate at base; corolla funnel-shaped, 1.5–4 cm long, sparsely pubescent, pink, lilac, mauve or purple, throat and lower lobe often cream with dark lines, lower lobe broadly ovate and longer than other lobes; stamens 4, inserted near base of corolla tube and included; ovary superior, 2-celled but each cell almost to apex divided by a false septum, style long and slender, with 2-lobed stigma. Fruit an oblong-quadrangular capsule 1–2 cm long, compressed laterally, with slender lateral horns up to 3.5 mm long, loculicidally dehiscent, many-seeded. Seeds broadly obovate in outline, compressed laterally, 2.5–4 mm × 2–2.5 mm, testa smooth but radially rugose at margin, usually black when ripe.

Emollient and lubricant (mucilage of leaves); aphrodisiac (plant); antioxidant, anti-inflammatory, antihypertensive, cytotoxic, antitumour and insecticidal (seed oil)

Ceratotheca sesamoides

A decoction of the plant is used against diarrhoea. Leaves are steeped in water and the slimy liquid is dropped into the eye to treat conjunctivitis. Leaves are warmed, ground, mixed with ash and rubbed on inflamed cervical lymph nodes. Leaves ground with the rhizome of Anchomanes difformis (Blume) Engl. are applied topically in cases of leprosy. The plant is used against jaundice, snakebites and skin diseases.