Euphorbia herbstii, a member of the Euphorbiaceae (spurge) family, is a small tree ranging from 3 to 8 m (10 to 26 ft) tall. The thin, leathery leaves, normally 8 to 19.5 cm (3.1 to 7.7 in) long and 1.8 to 3.8 cm (0.7 to 1.5 in) wide, are narrowly oblong or sometimes more lance-shaped or elliptic. The leaves are arranged in pairs on the same plane. The small, petal-less flower clusters (cyathia or compact flowering stalks with small individual flowers, the whole simulating a single flower) occur in groups of 3 to 15 in branched, open flowering stalks. The individual flower stalks are 8 to 20 mm (0.3 to 0.8 in) long. The hairy inflorescence bracts (specialized leaves) are broadly bell-shaped and contain 5 to 6 yellowish green glands. The green or sometimes reddish purple-tinged, angular capsules (dry fruit that open at maturity) scarcely protrude from the bracts.