Perennial subshrub or herb, usually erect, 30–100 cm high and at least somewhat woody at the base, sometimes sprawling. Leaves opposite, borne on short petioles, 2.5–9.0 cm long, usually elliptical to obovate, green with paler veins (at least in living plants); leaf apex rounded to acute with a tiny point extending from the midrib. Stems and leaves usually pubescent, sometimes hairless. Flowers borne in leaf axils, either singly or paired on very short stalks. Sepals 5, 2–6 mm long, narrow, usually pubescent. Corolla salverform, with a long narrow tube and lobes that spread perpendicular to the tube and almost flat (like a tray or "salver"); corolla tube greenish, usually at least 2.2 cm long, with the inside of the mouth often dark pink or sometimes yellow, pubescent inside the throat with rings of stiff hairs below the mouth and anthers; corolla lobes 5, pink to white or pinkish purple, 1.0–2.8 cm long, obovate. Anthers 5, attached to the inside of the corolla tube in the upper portion and concealed within it. Ovary split into two separate carpels, which above those are fused into a single style and a pistil head having a complicated structure, with a recurved basal veil and a densely pubescent ring below the cylinder that bears the stigma lobes. Fruit two narrow, linear-cylindrical follicles developing from the separate carpels, often only one maturing per flower, 2.0–4.7 cm long, with numerous small black seeds.

References

Forster, P. I. 1996. Apocynaceae.  Fl. Australia 28: 104–196.

Li P.-T., A. J. M. Leeuwenberg, and D. J. Middleton. 1995. Apocynaceae. Pp. 143–188 in Wu Z.-Y. and P. H. Raven, eds., Flora of China vol. 16. Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis, MO.

Markgraf, F. 1976. Apocynacées. Fl. Madagascar 169: 1–318.

Plaizier, A. C. 1985. Catharanthus. Fl. Zambesiaca 7(2): 453–456.

van Bergen, M. A. 1996. Revision of Catharanthus G. Don.  Series of revisions of Apocynaceae XLI. Wageningen Agricultural University Papers 96-3: 9–46.