Euphorbia radians |
Euphorbia mendezii |
|
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sun spurge |
Mendez's sandmat |
|
Habit | Herbs, perennial, with moniliform tuberous rootstock. | Herbs, annual or perennial, with slender taproot. |
Stems | erect, 5–20(–30) cm, usually glabrous, occasionally puberulent; branches ± straight. |
prostrate, often mat-forming, 8–35 cm, usually villous along margins, lower surface glabrous, upper surface usually strigillose to puberulent, rarely glabrous or glabrate. |
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 or connate basally, rarely completely connate, deltate, laciniate, glabrous or pilose (lower side), forming narrow deltate scale, sometimes apically 2-fid or laciniate, glabrous (upper side), 0.4–1.9 mm; petiole 0.3–1.2 mm, glabrous, pilose or villous; blade oblong to obovate, 4–12 × 2–7 mm, base asymmetric, one side attenuate, cuneate or rounded, other rounded or cordate, margins serrulate at least distally, apex obtuse, surfaces glabrous or sparsely sericeous, pilose or villous; 3-veined at base. |
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 or obconic, 0.8–1 × 0.7–0.8 mm, usually glabrous, rarely sparsely pilose toward apex; glands 4, pink, reniform, oblong or elliptic, 0.1 × 0.2–0.3 mm; appendages absent or white to pink, oblong, flabellate or forming narrow rim around edge of gland, 0.1–0.3 × 0.3–0.6 mm, distal margin usually entire, sometimes lobed. |
Staminate flowers | 20–25. |
6–15. |
Pistillate flowers | ovary glabrous or puberulent, styles 3–4 mm, 2-fid 1/2 to nearly entire length. |
ovary usually pilose or villous with hairs concentrated along keels, rarely glabrous; styles 0.2–0.3 mm, 2-fid 1/2 length. |
Capsules | depressed-globose, 3.8–5 × 4–5 mm, 3-lobed, glabrous or puberulent; columella 3.6–4.5 mm. |
ovoid, 1.2–1.6 × 1.2–1.4 mm, usually pilose or villous with hairs concentrated along keels, often glabrous in between, very rarely completely glabrous; columella 1–1.4 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. |
reddish brown to orange or gray-pink, narrowly ovoid, 4-angled in cross section, 0.9–1.2 × 0.5–0.6 mm, almost smooth or with 5–7 faint transverse ridges that do not pass through abaxial keel. |
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. |
|
Cyathia | peduncle 2–5.5 mm. |
solitary at nodes or on short, congested axillary branches; peduncle 0.9–2.5 mm. |
Euphorbia radians |
Euphorbia mendezii |
|
Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting year-round. |
Habitat | Pinyon-juniper woodlands, oak savannas, desert grasslands and scrub. | Disturbed areas. |
Elevation | 700–2500 m. (2300–8200 ft.) | 0–10 m. (0–0 ft.) |
Distribution |
AZ; TX; Mexico
|
FL; Mexico; Central America; West Indies; n South America [Introduced in North America] |
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 mendezii is a common weed distributed widely throughout Mexico and Central America. Within the flora area the species is known only from southern Florida. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 324. | FNA vol. 12, p. 277. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Poinsettia radians | Chamaesyce mendezii |
Name authority | Bentham: Pl. Hartw., 8. (1839) | Boissier: Cent. Euphorb., 15. (1860) |
Web links |