62. Euphorbia missurica Rafinesque, Atlantic J. 1: 146. 1832.
Prairie or Missouri spurge, prairie sandmat Prairie or Missouri spurge, prairie sandmat
Chamaesyce missurica (Rafinesque) Shinners; Euphorbia missurica var. intermedia (Engelmann) L. C. Wheeler; E. petaloidea Engelmann var. intermedia Engelmann
Herbs, annual, with taproot. Stems erect or ascending, 10–60(–100) cm, glabrous, sometimes ± glaucous. Leaves opposite; stipules usually distinct, occasionally connate basally on one or both sides of stem, linear to triangular-subulate, usually deeply and irregularly fringed or lobed, rarely entire, 0.7–1.5 mm, glabrous; petiole 1–3 mm, glabrous; blade linear to narrowly oblong or narrowly lanceolate-oblong, (4–)8–30 × 3–7 mm, base symmetric or subsymmetric (usually narrower leaves), or slightly asymmetric and angled or short-tapered (wider leaves), margins entire, occasionally ± revolute, apex rounded to truncate, occasionally emarginate or mucronulate, abaxial surface pale green, adaxial surface light to bright green, both surfaces glabrous; venation obscure. Cyathia solitary or in small, cymose clusters these occasionally subtended by reduced, bractlike leaves at distal nodes or on congested, axillary branches; peduncle 1–5(–11) mm. Involucre broadly campanulate, 1.2–1.8 × 1.7–1.9 mm, glabrous; glands 4, yellowish green, broadly oblong to nearly circular, cupped or folded, 0.3–0.6 × 0.3–0.7 mm; appendages white or ± pinkish tinged, ovate to oblong-ovate, 0.4–2.5 × 1.1–1.7 mm, distal margin entire or slightly crenate or emarginate at tip. Staminate flowers 24–60. Pistillate flowers: ovary glabrous; styles 0.5–1.4 mm, 2-fid 1/2 length. Capsules broadly ovoid-globose, 1.9–2.5 × 2–2.5(–3) mm, glabrous; columella 1.8–2.1 mm. Seeds mottled whitish to brown, ovoid to broadly ovoid-triangular, bluntly 3-angled in cross section, 1.5–2 × 1.1–1.4 mm, smooth or slightly wrinkled.
Flowering and fruiting late spring–late summer. Glades, ledges, bluff tops (usually calcareous), dry upland forest margins, sandy or disturbed areas; 50–1500 m; Ark., Colo., Iowa, Kans., Mo., Mont., Nebr., N.Mex., N.Dak., Okla., S.Dak., Tex., Wyo.
Euphorbia missurica is similar to the western E. parryi but has a more upright growth habit and more conspicuous involucral gland appendages. Native occurrences have been documented from Minnesota (last collected in Ottertail County in 1936), but it appears to have been extirpated from that state due to habitat loss to agriculture.