Euphorbia radians |
Euphorbia nephradenia |
|
---|---|---|
sun spurge |
Paria spurge, Utah spurge |
|
Habit | Herbs, perennial, with moniliform tuberous rootstock. | Herbs, annual, with slender little-branched taproot. |
Stems | erect, 5–20(–30) cm, usually glabrous, occasionally puberulent; branches ± straight. |
erect to ascending, branched, dichotomous distally and slightly angled, 4–25 cm, glabrous or sparsely strigillose. |
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 0.1–0.2 mm; petiole 2–6 mm, glabrous or sparsely strigillose; blade usually linear- to narrowly-elliptic, occasionally ovate to obovate, 14–42 × 3–10 mm, progressively narrower distally, base attenuate, margins entire, apex usually acute, rarely obtuse, surfaces glabrous or sparsely strigillose; 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, 1–1.1 × 1.2–1.4 mm, strigillose at least toward apex; glands 5, green-yellow, oblong, 0.4–0.6 × 0.7–1 mm; appendages whitish to yellow-green, lunate to broadly ovate, 0.2–0.5 × 0.7–1.1 mm, entire or slightly crenulate. |
Staminate flowers | 20–25. |
25–30. |
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 at apex. |
Capsules | depressed-globose, 3.8–5 × 4–5 mm, 3-lobed, glabrous or puberulent; columella 3.6–4.5 mm. |
oblate to subglobose, 2.9–3.2 × 3.2–3.4 mm, glabrous; columella 2.8–3.1 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. |
light gray to whitish, oblong-ovoid, rounded in cross section, 2.3–2.6 × 1.3–1.5 mm, dimpled and rugulose; caruncle absent. |
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 bifurcations of stems; peduncle 0.6–2.4 mm, glabrous or strigillose. |
Euphorbia radians |
Euphorbia nephradenia |
|
Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting spring–summer. |
Habitat | Pinyon-juniper woodlands, oak savannas, desert grasslands and scrub. | Saltbush, blackbrush, Ephedra-dominated scrub and desert communities. |
Elevation | 700–2500 m. (2300–8200 ft.) | 1100–1500 m. (3600–4900 ft.) |
Distribution |
AZ; TX; Mexico
|
CO; UT |
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 nephradenia is the only species of the genus endemic to the Colorado Plateau of Utah and adjacent Colorado. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 324. | FNA vol. 12, p. 249. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Alectoroctonum |
Sibling taxa | ||
Synonyms | Poinsettia radians | |
Name authority | Bentham: Pl. Hartw., 8. (1839) | Barneby: Leafl. W. Bot. 10: 314. (1966) |
Web links |