Euphorbia spathulata Lam.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Glabrous annual, 1–6 dm, often branched from the base; cauline lvs oblong-spatulate, 1–4 cm, obtuse, finely serrulate, the upper truncate or even subcordate at the sessile base; lvs subtending the umbel similar; lvs of the umbel shorter and relatively wider, broadly oblong to ovate or deltoid- ovate; rays of the primary umbel commonly 3, repeatedly dichotomous; involucre delicate, 0.8 mm; ovary and fr beset with numerous conic to cylindric processes, the fr 2.5 mm; seeds thick-lenticular, 1.5–1.8 mm, marked with a reticulum of fine, sharp, low ridges. Prairies, barrens, and rocky hills; Minn. and Mo. to Mont. and Tex., w. to the Pacific. May, June. (E. dictyosperma; Tithymalus arkansanus; T. missouriensis; Galarhoeus a.; G. m.)