19. Euphorbia spathulata Lam.

Map 1681, Pl. 383 g–i

Plants annual, with taproots. Stems 10–60 cm long, erect or ascending, unbranched below the inflorescence or occasionally few-branched, the branches not flattened toward the tip, usually green to yellowish green, sometimes faintly purplish-tinged, glabrous. Leaves alternate above the lowest node and below the inflorescence branches (those of the inflorescence branches usually opposite, those of the basal node opposite or whorled but usually absent at flowering), sessile. Stipules absent. Leaf blades 10–45 mm long, oblanceolate to oblong-oblanceolate (those of the leaves of the inflorescence branches broadly ovate to broadly ovate-triangular), unlobed, rounded to truncate or shallowly cordate at the base and sometimes somewhat clasping the stem, rounded or broadly angled to a bluntly pointed tip, the margins finely toothed mostly above the midpoint (the teeth sometimes minute and visible only with magnification), the surfaces glabrous, yellowish green to green. Inflorescences terminal umbellate panicles with a whorl of leaves at the base and each of the usually 3 primary branches often branched 1–3 additional times, the cyathia solitary at the branch tips and at the branch points. Involucre 0.6–0.9 mm long, glabrous, the rim shallowly 4- or 5-lobed to nearly entire, the marginal glands 4 or 5, 0.1–0.3 mm long, oblong-oval to elliptic or slightly kidney-shaped, greenish yellow to yellow, less commonly red or reddish-tinged, lacking a petaloid appendage. Staminate flowers 3–8 per cyathium. Ovaries glabrous, but the surface densely warty, the styles 0.3–0.8 mm long, each divided 1/4–1/2 of the way from the tip into 2(3) slightly club-shaped lobes. Fruits 2–3 mm long, glabrous but the surface finely warty. Seeds 1.3–1.7 mm long, broadly elliptic-ovate to nearly circular in outline, slightly biconvex in cross-section, rounded at the base, the surface with a fine network of low ridges, reddish brown to dark purplish brown but sometimes appearing slightly glaucous, with a pale, irregularly winglike caruncle, this often breaking off as the seeds are dispersed. May–July.

Scattered mostly in the western half of the state and uncommon in the eastern portion of the Ozark Division (Minnesota to Texas west to Washington and California). Glades, upland prairies, ledges and tops of bluffs, and less commonly banks of streams and rivers and bottomland forests; also ditches and railroads.