Euphorbia abramsiana |
Euphorbia angusta |
|
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Abrams' sandmat, Abrams' spurge |
Blackfoot sandmat, narrow-leaf spurge |
|
Habit | Herbs, annual, with slender taproot. | Herbs, perennial, with moderately to strongly thickened rootstock. |
Stems | prostrate, mat-forming, 10–35(–50) cm, shortly pilose or puberulent at least proximally, often glabrous distally. |
erect, 12–43 cm, uniformly strigose. |
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. |
opposite; stipules distinct, linear-subulate or nodiform to papilliform nodiform to papilliform stipules often reddish brown, 0.1–0.7 mm, strigose; petiole 0.3–1.2 mm, strigose; blade: proximal ovate to ovate-elliptic, distal linear to elliptic-linear, 7–41 × 2–5 mm, distal leaf blades more than 6 times as long as wide, base asymmetric, cuneate to rounded, margins entire, often involute on drying, apex acute, surfaces usually short strigose, occasionally glabrous adaxially; venation pinnate, 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. |
turbinate to campanulate-turbinate, 1–1.5 × 1–1.4 mm, strigose; glands 4, green to yellow-green, concave, narrowly oblong, 0.2–0.4 × 0.4–0.7 mm; appendages white, flabellate, 0.5–1.1 × 0.3–0.5 mm, distal margin shallowly and irregularly toothed. |
Staminate flowers | 3–5. |
16–26. |
Pistillate flowers | ovary glabrous; styles 0.1–0.3 mm, 2-fid nearly entire length. |
ovary strigose; styles 0.3–0.5 mm, 2-fid at apex to almost 1/2 length. |
Capsules | ellipsoid to ovoid, 1.3–1.5 × 1.1–1.5 mm, glabrous; columella 1–1.3 mm. |
broadly ovoid, 2–2.6 × 2.5–3 mm, strigose; columella 1.6–2.2 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, 4-angled in cross section, 1.7–2.2 × 1.1–1.2 mm, transversely low-ridged or 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 1.1–2.4 mm. |
2n | = 28. |
|
Euphorbia abramsiana |
Euphorbia angusta |
|
Phenology | Flowering and fruiting summer–fall. | Flowering and fruiting early spring–fall. |
Habitat | Desert scrub and desert grasslands. | Rocky limestone soils. |
Elevation | -40–1400 m. (-100–4600 ft.) | 400–1200 m. (1300–3900 ft.) |
Distribution |
AZ; CA; NM; TX; Mexico (Baja California, Baja California Sur, Sonora)
|
TX; Mexico (Coahuila) |
Discussion | Euphorbia angusta, which in the flora area is known from the trans-Pecos region to the Edwards Plateau, is easily recognized by its erect habit, linear leaves, and relatively showy involucral gland appendages with toothed margins. The species is closely related to E. acuta and the Mexican endemic E. johnstonii Mayfield (M. H. Mayfield 1991); it is not only morphologically distinctive but is also the only species in sect. Anisophyllum with C3 photosynthesis (R. F. Sage et al. 2011; T. L. Sage et al. 2011; G. L. Webster 1975). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
|
Source | FNA vol. 12, p. 259. | FNA vol. 12, p. 260. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Chamaesyce abramsiana | Chamaesyce angusta |
Name authority | L. C. Wheeler: Bull. S. Calif. Acad. Sci. 33: 109. (1934) | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 189. (1859) |
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