Euphorbia arizonica |
Euphorbia jaegeri |
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Arizona sandmat, Arizona spurge |
orocopia mountains spurge |
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Habit | Herbs, annual or short-lived perennial, with slender to slightly thickened taproot. | Shrubs, with woody rootstock. |
Stems | erect to ascending, 10–30 cm, uniformly pilose with glistening hairs. |
ascending, diffusely and intricately branched, 15–25 cm, usually puberulent to shortly hirsute, sometimes glabrate, bark grayish. |
Leaves | opposite; stipules distinct, deltate, (0–)0.1 mm, glabrous or with few scattered hairs; petiole 0.4–1.5 mm, pilose with glistening hairs; blade usually ovate, rarely elliptic, 3–11 × 2–7 mm, base asymmetric, one side cuneate to rounded, other side rounded to strongly cordate, margins entire, apex obtuse or acute, surfaces pilose with glistening hairs; 3-veined from base but usually only midvein conspicuous. |
opposite; stipules distinct or connate, subulate, 0.3–0.5 mm, puberulent; petiole 0.7–1.1 mm, puberulent to shortly hirsute; blade ovate or elliptic, 3–9 × 1.5–5 mm, base symmetric to slightly asymmetric, rounded to cuneate, margins entire, apex usually obtuse, sometimes acute, surfaces puberulent to shortly hirsute; 3-veined from base, often only midvein conspicuous. |
Involucre | urceolate, 1.1–1.3 × 0.5–0.9 mm, glabrous or pilose with glistening hairs; glands 4, dark maroon, usually oblong to reniform, rarely almost circular, 0.2 × 0.2–0.4 mm; appendages white to pink, oblong, flabellate, oblong, or elliptic, 0.3–0.6 × 0.6–0.9 mm, distal margin entire or crenulate. |
obconic to campanulate, 1.2–1.8 × 1.1–1.4 mm, puberulent to shortly hirsute; glands 4, yellow to pinkish, elliptic to oblong, 0.3 × 0.4–0.5 mm; appendages white to pink, 0.2–0.7 × 0.6–1.2 mm, irregularly divided from halfway to nearly base into 4–8 triangular to subulate segments, segments entire. |
Staminate flowers | 5–12. |
25–30. |
Pistillate flowers | ovary pilose, styles 0.5–0.6 mm, 2-fid 1/2 length. |
ovary canescent; styles 0.3–0.4 mm, 2-fid entire length. |
Capsules | broadly ovoid to subglobose, 1.4–1.8 mm diam., pilose; columella 1.1–1.4 mm. |
oblate, 1.7–2.3 × 1.8–2.7 mm, puberulent; columella 1.4–2 mm. |
Seeds | gray to light brown, ovoid, 4-angled in cross section, 0.9–1.1 × 0.5–0.6 mm, rugose with 2–5 irregular transverse ridges that sometimes pass through abaxial keel. |
tan to grayish, narrowly oblong-ovoid, ± 3–4-angled in cross section, 1.4–1.5 × 0.7–0.9 mm, irregularly dimpled or with faint transverse ridges that do not interrupt abaxial keel. |
Cyathia | solitary at distal nodes; peduncle 0.7–3.6 mm. |
solitary at distal nodes; peduncle 0.5–1.7 mm. |
Euphorbia arizonica |
Euphorbia jaegeri |
|
Phenology | Flowering and fruiting year-round in response to sufficient moisture. | Flowering and fruiting fall–spring. |
Habitat | Washes and rocky slopes, sometimes on limestone, desert scrub communities often with creosote-bush, riparian forests, mesquite woodlands, oak chaparral. | Desert scrub, hillsides, arroyos, primarily in rock crevices. |
Elevation | 100–1400 m. (300–4600 ft.) | 600–900 m. (2000–3000 ft.) |
Distribution |
AZ; CA; NM; TX; Mexico (Baja California, Baja California Sur, Chihuahua, Coahuila, Durango, Sonora)
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CA |
Discussion | Euphorbia arizonica is distinctive and easily recognized by its glistening, translucent hairs that appear somewhat glutinous and are most apparent on the stems. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia jaegeri is known only from the Orocopia Mountains of Riverside County and the Bristol and Marble Mountains of San Bernardino County. The species is one of few shrubby species of sect. Anisophyllum in the flora area. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 260. | FNA vol. 12, p. 273. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Chamaesyce arizonica | |
Name authority | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 186. (1859) | V. W. Steinmann & J. M. André: Aliso 30: 1, figs. 1–4. (2012) |
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