Euphorbia oblongata |
Euphorbia hooveri |
|
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Balkan spurge, egg-leaf spurge, oblong spurge |
Hoover's sandmat, Hoover's spurge |
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Habit | Herbs, perennial, with woody taproot. | Herbs, annual, with slender to slightly thickened taproot. |
Stems | erect, unbranched or densely branching, 80 cm, often densely villous (especially young stems and pleiochasial branches). |
prostrate, occasionally mat-forming, 4–10 cm, glabrous. |
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 or connate at base, deeply laciniate into numerous subulate to filiform segments, 0.3–1.3 mm, glabrous; petiole 0–0.5 mm, glabrous; blade broadly ovate, broadly oblong or suborbiculate, 3–7 × 2–5.5 mm, base asymmetric, hemiamplexicaulous, margin sharply serrulate to denticulate, teeth whitish and occasionally setaelike at apex, apex obtuse, surfaces papillate, glabrous; 3-veined from base, 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. |
campanulate, 1.2–1.5 × 1.5–2.2 mm, papillate; glands 4, yellow to reddish, subcircular to oblong, 0.4–0.5 × 0.5–0.7 mm; appendages white to pink, 0.3–0.9 × 0.7–1.6 mm, divided into 4–6 narrowly triangular, acute segments, these occasionally 2-fid, margins entire. |
Staminate flowers | 15–40. |
25–35. |
Pistillate flowers | ovary glabrous; styles 1.5–2 mm, 2-fid. |
ovary glabrous; styles 1.8–2.6 mm, unbranched, filiform. |
Capsules | globose, 3–4.5 × 3–4.5 mm, slightly 3-lobed; cocci rounded, verrucose-tuberculate, glabrous; columella 2.5–3.3 mm. |
oblate, 1.5–1.7 × 1.8–2.2 mm, glabrous; columella 1.2–1.4 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, inconspicuously 4-angled in cross section, 1.2–1.6 × 1–1.1 mm, rugose. |
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. |
|
Cyathia | peduncle 1–5 mm. |
solitary at distal nodes; peduncle 0.5 mm, stout. |
Euphorbia oblongata |
Euphorbia hooveri |
|
Phenology | Flowering and fruiting spring–fall. | Flowering and fruiting summer–fall. |
Habitat | Waste areas, disturbed sites, roadsides, fields, pastures. | Drying mudflats of vernal pools in grasslands and woodlands. |
Elevation | 30–900 m. (100–3000 ft.) | 20–200 m. (100–700 ft.) |
Distribution |
CA; OR; WA; s Europe [Introduced in North America]
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CA |
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 hooveri is federally listed as threatened; its populations are being affected severely by habitat loss and the invasion of exotic species. The species is endemic to vernal pools in six counties in the Central Valley of California. Molecular data show that E. hooveri is a hybrid species, closely related to E. albomarginata and E. serpens (Y. Yang and P. E. Berry 2011). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 305. | FNA vol. 12, p. 271. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Tithymalus oblongatus | Chamaesyce hooveri |
Name authority | Grisebach: Spic. Fl. Rumel. 1: 136. (1843) | L. C. Wheeler: Proc. Biol. Soc. Wash. 53: 9. (1940) |
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