Euphorbia ingens (SA Tree List No. 351), the naboom in Afrikaans, grows to 12 m. The rounded crown formed by numerous erect cactus-like stems resembles the shape of a hot-air balloon. The specific name ingens means large, great or huge in Latin.
At the base the trunk may measure 90 cm in diameter. The four or five angled branchlets have irregularly spaced constrictions forming segments along the length of each branchlet. There are paired spines on spaced dark spine shields, cushioned along the branchlet margins. The spines may often be absent on old trees. Between the margins the green smooth surfaces may be slightly wavy, especially on younger trees. The inflorescence is yellowish green, growing in clusters on upper branchlet margins. The almost spherical fruit is three-lobed, becoming red or purple as it ripens (Coates Palgrave, 2002; Noad and Birnie, 1994; www.plantzafrica.com).