Chamaesyce spurca (M. C. Johnston) B. L. Turner; C. theriaca (L. C. Wheeler) Shinners var. spurca (M. C. Johnston) Mayfield

Stems 5–25 cm. Leaf blade 3–7.1 × 1–3.5 mm. Cyathia usually solitary at distal nodes, rarely clustered on short, axillary branches; peduncle 0.6–1.3 mm. Involucre turbinate-campanulate to hemispheric, 1–1.8 × 0.9–1.4 mm; glands short-stipitate, subcircular, 0.2–0.5 × 0.2–0.5 mm; appendages present, occasionally rudimentary. Staminate flowers 20–36. Capsules 1.4–1.6 × 1.5–1.7 mm. Seeds with 3–4(–5) prominent transverse ridges.

Flowering and fruiting late winter–late fall. Desert scrub, limestone or igneous soils; 700–1500 m; N.Mex., Tex.; Mexico (Chihuahua, Coahuila).

Variety spurca is partly sympatric with var. theriaca in Brewster and Presidio counties but extends further west into Hudspeth and El Paso counties as well as into adjacent New Mexico.