21. Euphorbia tirucalli L., Sp. Pl. 452. 1753. Boiss. in DC.,Prodr. 15(2): 96. 1862. Hook. f., Fl. Brit. Ind. 5: 254. 1887; Parker, For. Fl. Punj. 446. 1918; Rech. f. & Schiman-Czeika, Fl. Iran. 6: 19. 1964; Stewart, Aim. Cat. Vasc. Pl. W. Pak. & Kashm. 453. 1972; Leach in Kirkia 9(1): 69. 1973.
Vern.: ‘African Milkbush’,’Milk hedge’.
An open-crowned, succulent-branched, unarmed ± glabrous shrub or small tree 2-6 m tall and 50-80 cm in girth. Bark brown, cracked. Wood moderately hard, strong. Branches spreading, terete, 1-1.5 cm thick, shrinking to c. 5 mm thick when dried, longitudinally finely whitish-striate and slightly grooved when fresh. Leaves alternate, sessile or subsessile, strongly deflexed, readily deciduous. Leaf-blades oblong-linear, 7-15 x 0.7-1.5 mm, obtuse at the apex, narrowed to the base, entire, thick, fleshy, subglabrous or glabrous. Stipules minute, discoid, glandular, dark purple or blackish. Cyathia small, densely crowded at the forks and tips of the branches; cyathophylls scarious. Glands peltate, transversely ovate to suborbicular, ochreous. Fruits rounded-trilobate, 8 x 8 mm, smooth, velutinous-subescent or subglabrous. Styles united to half-way, 3 mm long, bifid, stigmas capitate. Seeds ovoid-subglobose, 4 x 4 mm, smooth, minutely carunculate.
Lectotype: The figure in J. Commelin, ‘Horti Medici Amstel. Rar. Pl. 1:27, t. 14. or, 1697, of ‘Tithymalus indicus frutescens’ prepared from a plant grown at Amsterdam, Holland, introduced from Ceylon (now Sri Lanka) selected by L. Leach in Kirkia 9(1): 70-71, 1973, after consultation with Dr. W.T. Steam.
Fl. Per.: ‘in the hot weather’ (Parker).
Distribution: E. Africa, Angola; widely cultivated elsewhere in the tropics. Near sea-level. Cultivated as a hedge-plant.