Hairy-fruit spurge Hairy-fruit spurge

Euphorbia dentata Michaux var. cuphosperma Engelmann in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 190. 1859; Poinsettia cuphosperma (Engelmann) Small

Herbs, annual, with taproot. Stems erect, 13–20 cm, both pilose to villous and densely strigillose; branches ± straight. Leaves usually opposite, occasionally alternate at distal nodes; petiole 3–15 mm, pilose; blade narrowly to broadly elliptic, or lanceolate to ovate, 30–80 × 10–15 mm, base cuneate to rounded, margins coarsely crenate-dentate, strigose, revolute to nearly flat, apex broadly acute to acuminate, or obtuse, abaxial surface pilose, adaxial surface sparsely strigose-hirsute; venation pinnate, midvein prominent. Cyathial arrangement: terminal pleiochasial branches usually 3, occasionally reduced to congested cyme, 1–2-branched; pleiochasial bracts 2–4, often whorled, wholly green or paler green at base, similar in shape and size to distal leaves or slightly narrower; dichasial bracts highly reduced. Cyathia: peduncle 0.5–0.8 mm. Involucre campanulate to slightly cylindric, 2.3 × 1.2 mm, glabrous; involucral lobes divided into several linear, smooth lobes; gland 1, yellow-green, stipitate, clavate, 1–1.2 × 0.8–0.9 mm, opening bilabiate and oblong, glabrous; appendages absent. Staminate flowers 3–5. Pistillate flowers: ovary pilose; styles 1.2 mm, 2-fid nearly entire length. Capsules broadly ovoid, 2.2–3 × 1.9–2.7 mm, 3-lobed, pilose; columella 2–2.4 mm. Seeds gray-brown to pale gray, pyramidally ovoid, angular in cross section, 2.3–2.6 × 2.4–2.6 mm, coarsely tuberculate, tubercles in 2 transverse rows; caruncle 0.2–0.4 mm. 2n = 56.

Flowering and fruiting summer–fall. Open montane and canyon forests, pinyon-juniper forests, montane grasslands, stream beds, disturbed habitats; 800–2000 m; Ariz., N.Mex.; Mexico; Central America (Guatemala).