Plant: perennial herb milky sap; 15 cm-1 m tall from a fleshy rhizome; stinging hairs on stems, leaves, and inflorescences, 4-8 mm long, transparent, each borne on a conspicuous, swollen, whitish base Leaves: more or less round in outline, 8-15 cm in diameter, 3-5-lobed to about the middle, pubescent when young but soon glabrate between the stinging hairs; base broadly cordate; margin incised-dentate with aristate teeth 1-2.5 cm long, sparsely ciliate; petioles 2-10 cm long, with two large yellowish glands at apex; stipules 5-6 mm long, deeply lobed INFLORESCENCE: terminal cymes Flowers: STAMINATE FLOWERS numerous; calyx funnel-shaped, 9-14 mm long, armed with stinging hairs; stamens 10, all connate, with a ring of hairs at the base; staminodes 3, thread-like. PISTILLATE FLOWERS few; sepals oblanceolate to spatulate, 10-12 mm long, with a few stinging hairs; ovary pubescent but glabrate; styles twice-branched Fruit: capsule, 10-12 mm long, the stinging hairs dense. SEEDS 9-11 mm long, 6-7 mm wide, 4-4.5 mm thick, rounded on the back, angled on the inner face, brown, sometimes mottled; caruncle whitish, fleshy, ca. 3 mm wide. Misc: Dry plains and hillsides in grassland, desertscrub, and oak woodland; 1100-1600 m (3600-5200 ft); May-Sep REFERENCES: Levin, Geoffrey A. Euphorbiaceae. Part 1. Acalypha and Cnidoscolus. J. Ariz. - Nev. Acad. Sci. 29(1): 18.

Wiggins 1964, Kearney and Peebles 1969

Duration: Perennial Nativity: Native Lifeform: Forb/Herb General: Robust herb or slightly suffrutescent plant 1.5-12 dm tall from fleshy rhizome with stems, leaves, and inflorescences sparsely to densely armed with stiff stinging hairs 4-8 mm long, each hair surmounting a conspicuous, rounded, whitish pustule. Leaves: Petioles 2-10 cm long, blades orbicular to subreniform in outline, 8-15 cm wide, 3-5 lobed nearly to middle, broadly or shallowly subcordate at base, lobes coarsely incised-dentate, teeth 1-2.5 cm long, blade glabrous between bases of coarse stinging hairs. Papery stipules, whitish, 5-6 mm long. Flowers: Stout peduncles 1-5 cm long, monoecious flowers, staminate in broad cymes to 8 cm wide, staminate calyx white, papery, 9-14 mm long, funnelform, armed with spreading stinging hairs 2-5 mm long; pistillate calyx of 5 distinct, ligulate to oblanceolate segments 10-12 mm long, sparsely hispid with stinging hairs without, early deciduous. Fruits: Capsule 10-12 mm long, hispid. Ecology: Found on plains and hillsides from 2,500-5,000 ft (762-1524 m); flowers May-July. Notes: Notable for its transparent, stinging hairs from conspicuous, white, pustulate bases. Ethnobotany: Unknown Etymology: Cnidoscolus comes from Greek knide or nettle, and skolos, for thorn or prickle, while angustidens means narrow toothed. Synonyms: None Editor: SBuckley, 2010