Euphorbia bicolor |
Euphorbia abramsiana |
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snow-on-the-prairie |
Abrams' sandmat, Abrams' spurge |
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Habit | Herbs, annual, with taproot. | Herbs, annual, with slender taproot. |
Stems | erect, unbranched or branched, 40–100 cm, pilose. |
prostrate, mat-forming, 10–35(–50) cm, shortly pilose or puberulent at least proximally, often glabrous distally. |
Leaves | alternate; stipules 0.3–0.4 mm; petiole 0.3–1 mm, pilose; blade narrowly elliptic to lanceolate, 37–54 × 7–17 mm, base cuneate to slightly rounded, margins entire, apex aristate or acute, surfaces pilose; venation obscure, only midvein conspicuous. |
opposite; stipules distinct, divided into 5–7 subulate-filiform segments, 0.6–1.1 mm, usually glabrous, rarely pilose; petiole 0.5–1 mm, glabrous; blade ovate, elliptic-oblong, or slightly ovate-cordate, 3–11 × 2–5 mm, base asymmetric, truncate to hemicordate, margins serrulate at least toward apex, often entire toward base, apex acute to obtuse, surfaces sometimes with red spot in center, glabrous; usually only the midvein conspicuous. |
Involucre | campanulate, 2.7–3.5 × 2.2–3 mm, densely pilose; glands 4–5, green to pale greenish yellow, reniform, 0.6–0.7 × 1.4–1.6 mm; appendages white, obdeltate to orbiculate, 1.4–2.5 × 1.7–3 mm, dentate to erose. |
obconic, 0.5–0.6 × 0.4–0.5 mm, glabrous; glands 4, yellowish to pink, circular to oblong, 0.1 × 0.1–0.2 mm; appendages absent, or white to pink, semicircular to broadly ovate, to 0.1 × 0.2 mm, distal margin entire or shallowly lobed. |
Staminate flowers | 30–70. |
3–5. |
Pistillate flowers | ovary pilose; styles 0.7–1.2 mm, 2-fid 1/2 length. |
ovary glabrous; styles 0.1–0.3 mm, 2-fid nearly entire length. |
Capsules | depressed-ovoid, 3.5–7.5 × 6–8.7 mm, densely pilose; columella 4.5–5.5 mm. |
ellipsoid to ovoid, 1.3–1.5 × 1.1–1.5 mm, glabrous; columella 1–1.3 mm. |
Seeds | tan to brown, ovoid, 4.3–4.5 × 3.7–3.9 mm, alveolate; caruncle absent. |
light gray to light brown, narrowly ovoid to ovoid, 4-angled in cross section, 1–1.2 × 0.6–0.7 mm, with 3–5 prominent transverse ridges that often interrupt abaxial keel. |
Cyathia | in terminal pleiochasia dichasial and pleiochasial bracts linear to narrowly oblanceolate, with conspicuous white margins; peduncle 1.2–3 mm, densely pilose. |
solitary at distal nodes of primary stems or at nodes of short congested axillary branchlets; peduncle 0.2–0.5 mm. |
Euphorbia bicolor |
Euphorbia abramsiana |
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Phenology | Flowering and fruiting summer–fall. | Flowering and fruiting summer–fall. |
Habitat | Prairies, blackland (calcareous) prairies, pastures and clearings in former blackland prairie areas, roadside clearings. | Desert scrub and desert grasslands. |
Elevation | 100–200 m. (300–700 ft.) | -40–1400 m. (-100–4600 ft.) |
Distribution |
AR; LA; OK; TX
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AZ; CA; NM; TX; Mexico (Baja California, Baja California Sur, Sonora)
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Discussion | Euphorbia bicolor is similar in appearance to E. marginata but can be distinguished by its linear to narrowly oblanceolate bracts and the presence of hairs on all parts of the plant. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 12, p. 243. | FNA vol. 12, p. 259. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Alectoroctonum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Chamaesyce abramsiana | |
Name authority | Engelmann & A. Gray: Boston J. Nat. Hist. 5: 233. (1845) | L. C. Wheeler: Bull. S. Calif. Acad. Sci. 33: 109. (1934) |
Web links |