Euphorbia abramsiana |
Euphorbia fendleri |
|
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Abrams' sandmat, Abrams' spurge |
Fendler's sandmat |
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Habit | Herbs, annual, with slender taproot. | Herbs, perennial, with woody, thickened taproot. |
Stems | prostrate, mat-forming, 10–35(–50) cm, shortly pilose or puberulent at least proximally, often glabrous distally. |
usually prostrate, decumbent, or ascending, very rarely erect, often densely clustered from top of woody crown, 5–12 cm, glabrous. |
Leaves | 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. |
usually opposite, rarely whorled; stipules distinct, narrowly linear, 0.5–1 mm, glabrous; petiole 0.5–1 mm, glabrous; blade usually orbiculate to ovate, rarely almost lanceolate, 3–8 × 2.5–7 mm, base slightly asymmetric, slightly cordate to rounded or obtuse, margins entire, apex rounded to obtuse, surfaces glabrous; obscurely 3–5-veined from base, only midvein conspicuous. |
Involucre | 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. |
campanulate to turbinate or broadly cupulate, 1.1–1.7 × 1.2–1.8 mm, glabrous; glands 4, yellow-green to reddish, elliptic to oblong, 0.2–0.5 × 0.4–0.9 mm; appendages absent or white, rarely pink, often unequal, lunate to flabellate or sometimes forming crenate margin along gland, (0–)0.1–0.6 × (0–)0.5–1.5 mm, distal margin entire or toothed. |
Staminate flowers | 3–5. |
25–35. |
Pistillate flowers | ovary glabrous; styles 0.1–0.3 mm, 2-fid nearly entire length. |
ovary glabrous; styles 0.3–0.4 mm, 2-fid 1/2 length. |
Capsules | ellipsoid to ovoid, 1.3–1.5 × 1.1–1.5 mm, glabrous; columella 1–1.3 mm. |
depressed-globose, 2–2.4 × 2.2–2.5 mm, glabrous; columella 1.7–2.1 mm. |
Seeds | 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. |
white, ovoid-pyramidal, prominently 4-angled in cross section, 1.7–2 × 1–1.2 mm, smooth to slightly wrinkled. |
Cyathia | solitary at distal nodes of primary stems or at nodes of short congested axillary branchlets; peduncle 0.2–0.5 mm. |
solitary at distal nodes; peduncle 0.7–1.2 mm. |
2n | = 28. |
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Euphorbia abramsiana |
Euphorbia fendleri |
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Phenology | Flowering and fruiting summer–fall. | Flowering and fruiting spring–fall. |
Habitat | Desert scrub and desert grasslands. | Mountain slopes, desert scrub, pinyon-juniper woodlands, hills, canyons, grasslands, washes, roadsides, dry crevices in limestone, often in gravel and sand. |
Elevation | -40–1400 m. (-100–4600 ft.) | 500–2600 m. (1600–8500 ft.) |
Distribution |
AZ; CA; NM; TX; Mexico (Baja California, Baja California Sur, Sonora)
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AZ; CA; CO; KS; NE; NM; NV; OK; SD; TX; UT; WY; Mexico (Coahuila)
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Discussion | Euphorbia fendleri is similar to E. chaetocalyx and may sometimes be confused with that species. Its prostrate to decumbent or ascending stems and small, ovate to orbiculate leaves distinguish it from E. chaetocalyx. Some authors have used the presence or absence and shape of the involucral gland appendages to help separate E. fendleri from E. chaetocalyx, but those characters appear highly variable and of little taxonomic utility; somewhat intermediate individuals occur in western Arizona, New Mexico, and Texas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 12, p. 259. | FNA vol. 12, p. 267. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Chamaesyce abramsiana | Chamaesyce fendleri |
Name authority | L. C. Wheeler: Bull. S. Calif. Acad. Sci. 33: 109. (1934) | Torrey & A. Gray: in War Department [U.S.], Pacif. Railr. Rep. 2(4): 175. (1857) |
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