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The alkaloid fractions of ''Catharanthus lanceus'' have shown hypotensive activity. The main active compound is yohimbine, a potent α-adrenergic blocker, but several other compounds play a role as well. A lyophilized aqueous extract was found to show anti-tumour activity, with leurosine as the most potent compound. Some alkaloids have a hypoglycaemic effect. Leurocristine, perivine, periformyline and vincristine show antiviral activity in vitro against some human pathogens.

Perennial decumbent herb up to 1 m tall, with white latex; taproot carrot-shaped, up to 70 cm long; stems and branches reddish, almost quadrangular, internodes much longer than the leaves. Leaves opposite, simple and entire; stipules 1–3 at each side of the leaf base; petiole 1–3 mm long; blade oblong to narrowly ovate, 1–4.5 cm × 3–13 mm, base cuneate, apex acuminate to rounded, herbaceous to thinly leathery, shiny on both sides, glabrous. Flowers in leaf axils, bisexual, 5-merous, regular, fragrant; pedicel 5–25(–32) mm long; sepals slightly fused at base, 5–10 mm long; corolla tube cylindrical, 15–22 mm long, widening near the insertion of the stamens, throat constricted, inside with a ring of hairs just below the throat and a ring of hairs below the insertion of the stamens, green, pinkish at base, lobes ovate to obovate, 11–22 mm long, densely shortly hairy inside, spreading, pink, reddish violet or pale pink-magenta, white to cream at the base; stamens inserted just below the corolla throat, included, filaments very short; ovary superior, consisting of 2 very narrowly oblong carpels, style slender, 10–16 mm long, pistil head cylindrical with a reflexed transparent frill and with rings of woolly hairs at base and apex, stigma minute. Fruit composed of 2 free cylindrical follicles 1.5–5 cm long, striate, glabrous, green, dehiscent, 10–20-seeded. Seeds oblong, 1–3 mm long, grooved at one side, black. Seedling with epigeal germination.

''Catharanthus'' comprises 8 species, all originating from Madagascar except for ''Catharanthus pusillus'' (Murr.) G.Don, which is restricted to India and Sri Lanka. ''Catharanthus lanceus'' flowers and fruits from September to May.

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