Euphorbia graminea |
Euphorbia platysperma |
|
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grassleaf spurge |
dune spurge, flat-seed spurge, flatseed sandmat |
|
Habit | Herbs, usually annual, rarely perennial, with slender, rarely tuberous, taproot. | Herbs, annual or short-lived perennial, with slender taproot. |
Stems | erect or ascending, branched, 30–80(–110) cm, strigillose or glabrescent, sharply angled. |
prostrate, spreading and often mat-forming, 10–100 cm, glabrous. |
Leaves | usually alternate, sometimes some opposite; stipules usually 0.2–0.5 mm, rarely rudimentary; petiole 0.4–5.9 mm, strigillose; blade ovate, elliptic, linear-elliptic, or oblong, 10–83 × 3–39 mm, base attenuate, rounded, or cuneate, margins entire, apex acute or obtuse, surfaces strigillose; venation occasionally obscure on narrow leaves, midvein conspicuous. |
opposite; stipules usually distinct, occasionally connate basally, rarely to middle, subulate, narrowly triangular, or divided into 2–4 subulate segments, 0.5–1.1 mm, glabrous; petiole 1–3.6 mm, glabrous; blade oblong to obovate, 5–12 × 3–5 mm, base subsymmetric, cuneate to attenuate, margins entire, apex usually acute to mucronulate, rarely obtuse, surfaces glabrous; only midvein conspicuous. |
Involucre | campanulate or obconic, 1–1.8 × 0.8–1.7 mm, glabrous or strigillose toward rim; glands (1–)2–4, yellow to greenish, elliptic or oblong, 0.1–0.3 × 0.2–0.4 mm; appendages white to tinged purple, ovate and often hoodlike or forming narrow rim around distal margin of gland, 0.3–1.6 × 0.4–0.9 mm, entire. |
campanulate to obconic, 1.5–2 × 1.3–2.5 mm, glabrous; glands 4, yellowish, subcircular to oblong, 0.5–0.6 × 0.5–0.6 mm; appendages white, ovate to oblong or almost triangular, 0.3–0.6 × 0.3–0.8 mm, distal margin entire or shallowly 2–3-lobed. |
Staminate flowers | 30–40. |
45–50. |
Pistillate flowers | ovary glabrous; styles 0.7–1 mm, 2-fid from 1/2 to nearly entire length. |
ovary glabrous, styles 0.4–0.6 mm, 2-fid 1/2 length. |
Capsules | ovoid-oblate, 2.5–3 × 3–3.5 mm, glabrous; columella 1.6–1.9 mm. |
ovoid to ellipsoid, 2.7–3.2 × 2.2–2.9 mm, glabrous; columella 2.6–2.8 mm. |
Seeds | gray, brown, or nearly black, ovoid, circular or weakly angled in cross section, 1.5–1.7 × 1.3–1.5 mm, coarsely tuberculate with longitudinal rows of shallow pits; caruncle absent or punctiform, 0.1–0.2 mm. |
whitish, pinkish, or light brown, ellipsoid-oblong, weakly dorsiventrally compressed and semielliptic in cross section, 2.2–2.5 × 1.3–1.6 mm, with sharp linelike longitudinal ridge on adaxial side, smooth and rounded on back. |
Cyathia | in usually terminal, rarely axillary, dichasia, distal dichasial bracts often white; peduncle 0.4–4.5 mm (to 15 mm at first node of inflorescence), glabrous. |
solitary at distal nodes; peduncle 1.6–4.1 mm. |
Euphorbia graminea |
Euphorbia platysperma |
|
Phenology | Flowering and fruiting year-round. | Flowering and fruiting year-round in response to sufficient moisture. |
Habitat | Disturbed, weedy, or urban areas. | Sand dunes in Sonoran Desert scrub. |
Elevation | 0–500 m. (0–1600 ft.) | 60–200 m. (200–700 ft.) |
Distribution |
AR; CA; FL; LA; TX; Mexico; Central America; South America [Introduced in North America; introduced also in West Indies, Asia, Pacific Islands]
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AZ; CA; Mexico (Baja California, Sonora) |
Discussion | Euphorbia graminea occurs natively from northern South America to northern Mexico. The species is a variable and taxonomically complex entity whose boundaries are not well defined and are in need of further study. Euphorbia graminea is often weedy and has recently become established in warmer areas of the southern United States, where it will likely become more common in the future. In recent years, a cultivar of E. graminea has found considerable horticultural success and is marketed under the trade name "Diamond Frost." (Discussion copyrighted by Flora of North America; reprinted with permission.) |
|
Source | FNA vol. 12, p. 246. | FNA vol. 12, p. 282. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Alectoroctonum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Chamaesyce platysperma | |
Name authority | Jacquin: Select. Stirp. Amer. Hist., 151. (1763) | Engelmann: in W. H. Brewer et al., Bot. California 2: 482. (1880) |
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