Euphorbia radians |
Euphorbia melanadenia |
|
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sun spurge |
red-gland spurge, squaw sandmat |
|
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. |
ascending to erect, 5–20 cm, sericeous to appressed-villous. |
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 (lower side) and connate (upper side), linear, 0.5–1 mm, densely pilose; petiole 0.8–1.5 mm, tomentose; blade ovate, 1.2–5 × 0.8–2.9 mm, base asymmetric, hemicordate, margins entire, apex rounded to acute, surfaces tomentose; venation inconspicuous. |
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, 0.6–1.1 × 0.7–1 mm, tomentose; glands 4, deep red to purple, elliptic, 0.3–0.4 × 0.4–0.7 mm; appendages white or becoming pink with age, oblong to flabellate, 0.4–0.7(–1) × 0.7–1.2 mm, distal margin entire or erose. |
Staminate flowers | 20–25. |
45–80. |
Pistillate flowers | ovary glabrous or puberulent, styles 3–4 mm, 2-fid 1/2 to nearly entire length. |
ovary tomentose, 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, 1.4–1.8 × 1.4–1.7 mm, tomentose; columella 1.2–1.5 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 to tan, oblong, 4-angled in cross section, 1–1.2 × 0.4–0.6 mm, smooth to wrinkled or alveolate. |
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 distal nodes; peduncle (0.6–)1.4–1.9 mm. |
Euphorbia radians |
Euphorbia melanadenia |
|
Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting year-round. |
Habitat | Pinyon-juniper woodlands, oak savannas, desert grasslands and scrub. | Rocky slopes, river washes, dry to wet soils. |
Elevation | 700–2500 m. (2300–8200 ft.) | 400–1400 m. (1300–4600 ft.) |
Distribution |
AZ; TX; Mexico
|
AZ; CA; Mexico (Baja California, Sonora)
|
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 melanadenia is similar in appearance to E. cinerascens, but E. melanadenia has conspicuous involucral gland appendages whereas E. cinerascens has inconspicuous appendages or lacks them entirely. Euphorbia melanadenia occurs in Arizona and southern California, whereas E. cinerascens is found only in southern and western Texas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 324. | FNA vol. 12, p. 276. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Poinsettia radians | Chamaesyce melanadenia |
Name authority | Bentham: Pl. Hartw., 8. (1839) | Torrey: in War Department [U.S.], Pacif. Railr. Rep. 4(5): 135. (1857) |
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