Euphorbia schizoloba |
Euphorbia innocua |
|
---|---|---|
Mojave spurge |
velvet spurge |
|
Habit | Herbs, perennial, with thick rootstock. | Herbs, perennial, with moderately to strongly thickened rootstock. |
Stems | slender, ascending, often sinuous, many, densely branched near base, 10–50 cm, usually glabrous, usually glaucous. |
prostrate to decumbent or ascending, branched (often near base), 7–45 cm, densely pilose. |
Leaves | petiole 0–1 mm; blade broadly oblanceolate to obovate, 10–20 × 3–9 mm, base usually acute, occasionally short-attenuate, rarely obtuse, margins entire, apex usually acute, occasionally obtuse, acuminate to cuspidate, surfaces usually glabrous, usually glaucous; venation pinnate, sometimes obscure, midvein prominent. |
alternate; stipules to 0.1 mm; petiole (0.7–)1.1–3.5 mm, pilose; blade ovate to orbiculate, 4.6–17(–25) × 4.5–15(–19) mm, base cordate, margins entire, apex rounded to obtuse, surfaces densely pilose; venation obscure, usually only midvein conspicuous. |
Involucre | campanulate to broadly turbinate, 2.2–3 × 2–2.5 mm, glabrous; glands 4, irregularly semicircular to trapezoidal or elliptic-truncate, 0.8–1.5 × 1–2.2, margins strongly crenate or dentate; horns usually absent, if present then straight, 0.1–0.2 mm, generally equaling teeth on gland margin. |
campanulate, 1–1.3 × 1.2–1.4 mm, pilose; glands 4, yellow to green, elliptic, 0.2–0.3 × 0.5–0.6 mm; appendages green, elliptic, 0.4–0.5 × 0.5–0.9 mm, entire or crenulate, ciliate. |
Staminate flowers | 12–20. |
5–10. |
Pistillate flowers | ovary glabrous; styles 1–1.2 mm, 2-fid. |
ovary pilose; styles 0.4–0.7 mm, 2-fid 1/2 length. |
Capsules | oblong-ovoid, 3.5–4 × 3.8–5 mm, 3-lobed; cocci rounded, smooth, glabrous; columella 3.3–3.8 mm. |
depressed-ovoid, 2–2.5 × 2.7–3.3 mm, pilose; columella 1.6–2.1 mm. |
Seeds | gray to whitish, oblong cylindric, 2–3 × 1.5 mm, irregularly shallowly pitted to almost smooth; caruncle conic, 0.6 × 0.6 mm. |
gray to brown, ovoid, 1.5–1.7 × 1.2–1.3 mm, rugose with whitish ridges; caruncle absent. |
Cyathial | arrangement: terminal pleiochasial branches (1–)3–4(–5), each 1–3 times 2-branched; pleiochasial bracts broadly ovate to subcordate, usually similar in size to, occasionally wider than, distal leaves; dichasial bracts distinct, broadly ovate to almost reniform, base obtuse, margins entire, apex obtuse, acuminate to cuspidate; axillary cymose branches 0–2(–4). |
|
Cyathia | peduncle 0.3–1 mm. |
in terminal dichasia (often weakly defined); peduncle 1–2.7 mm, densely pilose. |
Euphorbia schizoloba |
Euphorbia innocua |
|
Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting early winter–late spring. |
Habitat | Desert mountains and canyon slopes, rocky and gravelly soils. | Sandy soils or dunes, grasslands, pastures. |
Elevation | 500–1800 m. (1600–5900 ft.) | 0–20 m. (0–100 ft.) |
Distribution |
AZ; CA; NV
|
TX |
Discussion | Euphorbia schizoloba is a desert perennial that occurs on bluffs and ledges in the Mojave and Sonoran Deserts. Sparsely pubescent plants of E. schizoloba are known from Arizona and are best represented by several collections from the Mazatzal and Sierra Ancha mountains in Gila County from between 1000 to 1800 meters. George Engelmann published two names for this species almost simultaneously in 1861 (E. schizoloba and E. incisa). Although the authors have not been able to determine which publication has priority, Engelmann himself cited E. incisa as a synonym of E. schizoloba (in W. H. Brewer et al. 1876–1880, vol. 2), as did J. B. S. Norton (1899). Also, the type specimen at MO was annotated by Engelmann as E. schizoloba, and there is no mention of the name E. incisa on the sheet. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia innocua is restricted to south coastal Texas in Aransas, Calhoun, Kenedy, Kleberg, Nueces, Refugio, San Patricio, and Willacy counties. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 309. | FNA vol. 12, p. 247. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Alectoroctonum |
Sibling taxa | ||
Synonyms | E. incisa, Tithymalus incisus, T. schizolobus | |
Name authority | Engelmann: Proc. Amer. Acad. Arts 5: 173. (1861) | L. C. Wheeler: Contr. Gray Herb. 127: 62, plate 3, fig. D. (1939) |
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