Natal plum

Arduina macrocarpa Ecklon, S. African Quart. J. 1: 372. 1830

Shrubs 1–2(–6) m. Stems: spines stout, bifurcated. Leaves: peti­ole 1–6 mm, glabrous; blade ovate, elliptic, oblong, or orbic­ulate, 1.3–7.2 × 0.9–5.3 cm, cor­iaceous, base cordate to cune­ate, margins revolute, apex acute or mucro­nate, glabrous. Peduncles 3–4 mm, glabrous. Pedicels 3–4 mm, glabrous. Flowers: calyx lobes ovate to narrowly oblong, auriculate, 2–4.5(–7) mm, glabrous, colleters present or absent; corolla glabrous abaxially, eglandular-pubescent adaxially, tube 5–10 × 1.5–2 mm, throat 5–12 × 2.5–3 mm, lobes spreading, obliquely obovate, (4.5–)10–24 × 4–7 mm. Berries 2.7–6 × 2–3 cm. Seeds 4–6 × 3–4.5 mm. 2n = 22.

Flowering spring–fall; fruiting summer–fall. Coastal hammocks, beach dunes, disturbed areas; 0–10 m; introduced; Fla., Tex.; e, se Africa; cultivated widely in warmer parts of the world.

The stout, dichotomously branched spines readily distinguish Carissa macrocarpa from all other North American members of Apocynaceae. Plants are widely cultivated as ornamentals and for hedges in warmer parts of the United States and have become naturalized in a few coastal counties in Florida and Texas. The flesh of the fruit is edible when fully ripe, but unripe fruits, seeds, and all vegetative parts of the plant are toxic.