Euphorbia radians |
Euphorbia cordifolia |
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sun spurge |
heartleaf sandmat |
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Habit | Herbs, perennial, with moniliform tuberous rootstock. | Herbs, annual, with taproot. |
Stems | erect, 5–20(–30) cm, usually glabrous, occasionally puberulent; branches ± straight. |
prostrate, occasionally mat-forming, 10–43 cm, glabrous. |
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 usually distinct, occasionally connate at base, filiform, 1–1.2(–2.8) mm, usually glabrous, rarely pilose; petiole 0.4–1 mm, usually glabrous; blade ovate to oblong, 4.4–12 × 2.6–7.6 mm, base asymmetric, cordate to rounded, margins entire, apex rounded to mucronulate, surfaces glabrous; 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. |
campanulate, 1–1.3 × 1–1.3 mm, glabrous; glands 4, yellowish to pink, elliptic, 0.3–0.5 × 0.5–1 mm; appendages whitish to pink, sometimes drying red, elliptic to ovoid, 1.1–1.5 × 1.2–1.9 mm, distal margin entire, retuse, or erose. |
Staminate flowers | 20–25. |
5–40. |
Pistillate flowers | ovary glabrous or puberulent, styles 3–4 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous; styles 0.5–0.8 mm, 2-fid nearly entire length. |
Capsules | depressed-globose, 3.8–5 × 4–5 mm, 3-lobed, glabrous or puberulent; columella 3.6–4.5 mm. |
ovoid, 2–3 mm diam., glabrous; columella 1.2–2.7 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. |
gray or tan with dark brown mottling, ovoid, bluntly 3–4-angled in cross section, 1.8–2.1 × 1.2–1.4 mm, smooth to rugose. |
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 0.9–3 mm. |
Euphorbia radians |
Euphorbia cordifolia |
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Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting summer–fall. |
Habitat | Pinyon-juniper woodlands, oak savannas, desert grasslands and scrub. | Xeric oak-pine scrub, pine-barrens, sand barrens, sandy stream banks. |
Elevation | 700–2500 m. (2300–8200 ft.) | 0–200 m. (0–700 ft.) |
Distribution |
AZ; TX; Mexico
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AL; AR; FL; GA; LA; MS; NC; OK; SC; TX
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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.) |
Euphorbia cordifolia is easily identified by its cordate to rounded leaf base and distinctive filiform stipules. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 324. | FNA vol. 12, p. 265. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Poinsettia radians | Chamaesyce cordifolia |
Name authority | Bentham: Pl. Hartw., 8. (1839) | Elliott: Sketch. Bot. S. Carolina 2: 656. (1824) |
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