Euphorbia radians |
Euphorbia helioscopia |
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sun spurge |
euphorbe réveille-matin, mad woman's milk, summer spurge, sun spurge, wart spurge, wartweed |
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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. |
erect, unbranched or branched, 5–45 cm, usually glabrous or sparsely pilose. |
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. |
petiole absent or to 0.5 mm; blade obovate-spatulate, 4–40 × 2–25 mm, base cuneate, attenuate, or auriculate, margins serrulate, apex rounded, surfaces glabrous; venation pinnate, midvein prominent. |
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. |
cupulate, 1.5–2 × 0.7–1.1 mm, glabrous; glands 4, elliptic, 0.2–0.5 × 0.5–1 mm; horns absent. |
Staminate flowers | 20–25. |
10–15. |
Pistillate flowers | ovary glabrous or puberulent, styles 3–4 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous; styles 0.7–1 mm, 2-fid. |
Capsules | depressed-globose, 3.8–5 × 4–5 mm, 3-lobed, glabrous or puberulent; columella 3.6–4.5 mm. |
depressed-globose, 2.5–4 × 3.2–4.2 mm, clearly 3-lobed; cocci rounded, smooth, glabrous; columella 0.9–1.1 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. |
dark brown to blackish, subovoid, 1.6–2.2 × 1.5–1.9 mm, reticulate; caruncle elliptic, 0.9–1.1 × 0.4–0.5 mm. |
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. |
arrangement: terminal pleiochasial branches (3–)5, each 1–2 times 2-branched; pleiochasial bracts obovate, wider than distal leaves; dichasial bracts distinct, obovate or rhombic, ± oblique, base rounded, truncate, or attenuate, margins serrulate, apex rounded; axillary cymose branches 0. |
Cyathia | peduncle 2–5.5 mm. |
peduncle 0.2–1 mm. |
Euphorbia radians |
Euphorbia helioscopia |
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Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting spring–fall. |
Habitat | Pinyon-juniper woodlands, oak savannas, desert grasslands and scrub. | Roadsides, waste places. |
Elevation | 700–2500 m. (2300–8200 ft.) | 0–1400 m. (0–4600 ft.) |
Distribution |
AZ; TX; Mexico
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CA; CT; DC; DE; GA; ID; IL; LA; MA; MD; ME; MI; MT; NC; NH; NJ; NY; OH; OR; PA; SC; TN; TX; VA; VT; WA; WI; WY; AB; BC; NB; NF; NS; ON; PE; QC; SK; Europe; Asia; n Africa [Introduced in North America; introduced also in South America (Argentina, Chile)]
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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 helioscopia was collected once in Minnesota in the late 1800s but apparently did not become established there. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 324. | FNA vol. 12, p. 303. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | Poinsettia radians | Galarhoeus helioscopius, Tithymalus helioscopius |
Name authority | Bentham: Pl. Hartw., 8. (1839) | Linnaeus: Sp. Pl. 1: 459. (1753) |
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