Blackseed Spurge

Description

Euphorbia bilobata Engelmann in W. H. Emory, Rep. U.S. Mex. Bound. Herbs, annual, with slender taproot. Stems erect, branched, 10-35 cm, glabrous or strigillose (especially when young and around nodes). Leaves opposite proximally, alternate distally; stipules 0.1-0.2 mm; petiole 1-4 mm, glabrous, sericeous or strigillose; blade linear to narrowly elliptic, 8-52 - 2-7 mm, base attenuate, margins entire, ciliate-strigose, apex acute, abaxial surface sparsely strigillose to sericeous, adaxial surface usually glabrous; venation obscure, only midvein conspicuous. Cyathia solitary at distal nodes or in weakly defined cymes or dichasia, dichasial bracts and distal stem leaves wholly green; peduncle 0.5-3.6 mm, strigillose. Involucre obconic, 0.9-1.5 - 0.9-1.3 mm, strigillose to pilose; glands 5, yellow or pink, U-shaped, 0.2-0.3 - 0.4-0.5 mm; appendages greenish, white, or pink, forming narrow rim around gland, or ovate, oblong, or obovate and usually 2-fid, rarely rudimentary, 0.2-1.4 - 0.2-0.6 mm, entire. Staminate flowers 20-25. Pistillate flowers: ovary glabrous, puberulent, strigillose, or pilose; styles 0.5-0.8 mm, 2-fid 1/3-1/2 length. Capsules oblate, 1.5-2.6 - 2.1-3.3 mm, glabrous or puberulent, strigillose, or pilose; columella 1.2-2.1 mm. Seeds brown to grayish black, narrowly ovoid, 3- or 4-angled in cross section, sometimes obscurely so, 1.3-1.9 - 1-1.4 mm, tuberculate, often with shallow depressions; caruncle absent. 2n = 32. Flowering and fruiting spring-fall. Sandy and rocky soils on slopes and canyon bottoms in pine-juniper woodlands, oak woodlands, grasslands; 1400-2600 m; Ariz., N.Mex., Tex.; Mexico (Chihuahua, Durango, Sonora).