Euphorbia oblongata |
Euphorbia arizonica |
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Balkan spurge, egg-leaf spurge, oblong spurge |
Arizona sandmat, Arizona spurge |
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Habit | Herbs, perennial, with woody taproot. | Herbs, annual or short-lived perennial, with slender to slightly thickened taproot. |
Stems | erect, unbranched or densely branching, 80 cm, often densely villous (especially young stems and pleiochasial branches). |
erect to ascending, 10–30 cm, uniformly pilose with glistening hairs. |
Leaves | petiole absent; blade oblong to narrowly obovate or lanceolate, 15–70 × 6–25 mm, base rounded or truncate, margins finely serrulate, apex obtuse, mucronulate, surfaces glabrous; venation inconspicuously pinnate, midvein prominent. |
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. |
Involucre | cupulate to slightly turbinate, 1.5–2.5 × 1.3–1.5 mm, glabrous; glands 2–3, elliptic, 0.6–0.8 × 0.8–1.2 mm; horns absent. |
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. |
Staminate flowers | 15–40. |
5–12. |
Pistillate flowers | ovary glabrous; styles 1.5–2 mm, 2-fid. |
ovary pilose, styles 0.5–0.6 mm, 2-fid 1/2 length. |
Capsules | globose, 3–4.5 × 3–4.5 mm, slightly 3-lobed; cocci rounded, verrucose-tuberculate, glabrous; columella 2.5–3.3 mm. |
broadly ovoid to subglobose, 1.4–1.8 mm diam., pilose; columella 1.1–1.4 mm. |
Seeds | brown, ovoid, 2.4–2.6 × 1.3–2 mm, smooth, caruncle reniform, 0.2–0.3 × 0.8–0.9 mm. |
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. |
Cyathial | arrangement: terminal pleiochasial branches 3–5, each 2–3 times 2–4-branched; pleiochasial bracts ovate, similar in size to distal leaves; dichasial bracts distinct, ovate to suborbiculate, base truncate or rounded, margins entire or finely denticulate, apex obtuse, sometimes mucronulate; axillary cymose branches 0–4. |
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Cyathia | peduncle 1–5 mm. |
solitary at distal nodes; peduncle 0.7–3.6 mm. |
Euphorbia oblongata |
Euphorbia arizonica |
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Phenology | Flowering and fruiting spring–fall. | Flowering and fruiting year-round in response to sufficient moisture. |
Habitat | Waste areas, disturbed sites, roadsides, fields, pastures. | Washes and rocky slopes, sometimes on limestone, desert scrub communities often with creosote-bush, riparian forests, mesquite woodlands, oak chaparral. |
Elevation | 30–900 m. (100–3000 ft.) | 100–1400 m. (300–4600 ft.) |
Distribution |
CA; OR; WA; s Europe [Introduced in North America]
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AZ; CA; NM; TX; Mexico (Baja California, Baja California Sur, Chihuahua, Coahuila, Durango, Sonora)
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Discussion | Euphorbia oblongata is listed as a noxious weed by the states of California, Oregon, and Washington. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 12, p. 305. | FNA vol. 12, p. 260. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Tithymalus oblongatus | Chamaesyce arizonica |
Name authority | Grisebach: Spic. Fl. Rumel. 1: 136. (1843) | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 186. (1859) |
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