55. Euphorbia lata Engelmann in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 188. 1859.
Broadleaf spurge Broadleaf spurge
Euphorbia dilatata Torrey & A. Gray in War Department [U.S.], Pacif. Railr. Rep. 2(4): 175. 1857, not Hochstetter ex A. Richard 1850; Chamaesyce lata (Engelmann) Small; E. rinconis M. E. Jones
Herbs, perennial, with moderately thickened to robust rootstock. Stems ascending to erect, or prostrate, 10–25 cm, strigose to short-sericeous or ± villous. Leaves opposite; stipules distinct, filiform, 0.8–1.3 mm, strigose to short-sericeous or ± villous; petiole 0.5–2 mm, densely strigose to short-sericeous or ± villous; blade narrowly to broadly ovate-deltate, older ones often falcate, 4–12 × 3–7 mm, base asymmetric, obliquely rounded to obtuse, noticeably wider on one side, margins entire, often ± revolute, apex broadly acute, surfaces strigose to short-sericeous or ± villous; obscurely 3–5-veined from base, midvein prominent abaxially. Cyathia solitary at distal nodes; peduncle 1–3 mm. Involucre broadly campanulate, 2–2.5 × 2.2–2.6, strigose; glands 4, greenish, oblong to semilunate, 0.2–0.7 × 0.6–1 mm; appendages rudimentary or white, forming narrow band, (0–)0.1–0.2 × (0–)0.6–1 mm, distal margin entire or crenate. Staminate flowers 25–35. Pistillate flowers: ovary densely strigose to short-sericeous or ± villous; styles dark purplish, 0.8–1.2 mm, 2-fid 1/2 to nearly entire length. Capsules ovoid, 1.9–2.3 × 2–2.4 mm, strigose to short-sericeous or ± villous; columella 1.7–2.2 mm. Seeds whitish, oblong, 4-angled in cross section, faces concave, 1.5–1.8(–2) × 0.6–0.9 mm, smooth. 2n = 28, 56.
Flowering and fruiting spring–fall. Mountain slopes, canyons, basins, rocky prairies, roadsides, disturbed sites, usually in calcareous soils, sometimes in igneous-derived, sandy or rocky soils; 600–2200 m; Colo., Kans., N.Mex., Okla., Tex.; Mexico (Chihuahua, Coahuila).