Euphorbia radians |
Euphorbia cinerascens |
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sun spurge |
ashy sandmat |
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Habit | Herbs, perennial, with moniliform tuberous rootstock. | Herbs, perennial, with moderately to strongly thickened rootstock. |
Stems | erect, 5–20(–30) cm, usually glabrous, occasionally puberulent; branches ± straight. |
prostrate to decumbent, mat-forming, 5–30 cm, appressed wooly, strigillose, or short-sericeous. |
Leaves | alternate; petiole 0–2 mm, glabrous or strigose; blade linear-lanceolate to ovate or broadly elliptic, 25–50 × 3–20 mm, unlobed, base rounded (tapered to petiole), margins with few glandular teeth, strigillose, flat to revolute, apex acute, abaxial surface coarsely strigose, adaxial surface strigose-hirsute; venation pinnate, midvein prominent. |
opposite; stipules distinct, subulate, 0.2–0.5 mm, appressed wooly to sericeous; petiole 0.3–0.8 mm, appressed wooly to sericeous; blade ovate to elliptic, 1.5–5.5 × 1.3–4 mm, base asymmetric, obtuse to hemicordate, margins entire often reddish, apex usually obtuse, occasionally acute (young leaves), surfaces sericeous to strigillose or slightly pilose, adaxial surface often glabrous; 3-veined from base but only midvein conspicuous. |
Involucre | broadly globose-cupulate, 1.7–2.1 × 2.2–2.5 mm, glabrous or puberulent; involucral lobes divided into triangular segments; glands 1–4(–5), white, sessile and broadly attached, 1.1 × 1.4 mm, opening oblong, glabrous; appendages absent. |
turbinate, 0.8–1.3 × 1.2–2 mm, appressed wooly, sericeous, or strigillose; glands 4, purple-black, elliptic to oblong, 0.2–0.3 × 0.4–0.6 mm; appendages absent or reddish pink, forming narrow rim around distal margin of gland, 0–0.1 × 0–0.6 mm, distal margin entire, crenulate, or erose. |
Staminate flowers | 20–25. |
15–20. |
Pistillate flowers | ovary glabrous or puberulent, styles 3–4 mm, 2-fid 1/2 to nearly entire length. |
ovary canescent; styles 0.3–0.5 mm, 2-fid at apex. |
Capsules | depressed-globose, 3.8–5 × 4–5 mm, 3-lobed, glabrous or puberulent; columella 3.6–4.5 mm. |
subglobose to broadly ovoid, 1.3–1.7 × 1.5–1.8 mm, canescent; columella 1–1.3 mm. |
Seeds | white, mottled brown to gray, ellipsoid, rounded in cross section, 4–4.6 × 2.4–3.2 mm, smoothly and broadly pitted or grooved; caruncle 0.1 mm. |
white to pinkish or light brown, ovoid, 4-angled in cross section, 1–1.4 × 0.6–0.8 mm, smooth to rugulose or rarely with 1–2 inconspicuous transverse ridges. |
Cyathial | arrangement: terminal pleiochasial branches usually 3, occasionally reduced to congested cyme, 1–2-branched (often highly condensed); pleiochasial bracts 6–8(–10), as tight involucrate whorl, wholly white to pale pink or red, usually narrower than distal leaves; dichasial bracts linear and highly reduced. |
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Cyathia | peduncle 2–5.5 mm. |
solitary at distal nodes; peduncle 0.2–0.3 mm. |
2n | = 32. |
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Euphorbia radians |
Euphorbia cinerascens |
|
Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting year-round (mostly spring–fall). |
Habitat | Pinyon-juniper woodlands, oak savannas, desert grasslands and scrub. | Desert scrub, oak and juniper woodlands, thorn scrub, shrublands, grasslands, frequently on limestone substrates. |
Elevation | 700–2500 m. (2300–8200 ft.) | 70–1400 m. (200–4600 ft.) |
Distribution |
AZ; TX; Mexico
|
TX; Mexico |
Discussion | Euphorbia radians is widely distributed but scattered from the Sonoran and Chihuahuan deserts south to Oaxaca in Mexico. The species is distinct among species in sect. Poinsettia in the flora area in its precocious habit, often flowering before the leaves emerge. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
In the flora area, Euphorbia cinerascens is found only in southern and western Texas. In Mexico, it is found from Chihuahua east to Tamaulipas, south to Guanajuato. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 324. | FNA vol. 12, p. 264. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Poinsettia radians | Chamaesyce cinerascens |
Name authority | Bentham: Pl. Hartw., 8. (1839) | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 186. (1859) |
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