Euphorbia ophthalmica |
Euphorbia bifurcata |
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Florida hammock sandmat |
fork spurge |
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Habit | Herbs, usually annual, rarely short-lived perennial, with slender to slightly thickened taproot. | Herbs, annual, with slender, fibrous taproot. |
Stems | usually prostrate, rarely ascending, 6–22 cm, usually both strigillose and hirsute. |
erect, 20–70 cm, glabrous or with few scattered spreading hairs; branches arcuate, branching appearing dichotomous. |
Leaves | opposite; stipules distinct, subulate-filiform, undivided or divided into 2–4 narrowly triangular to linear-subulate segments, no dark, circular glands at base of stipules, 0.9–1.5 mm, pilose or strigillose; petiole 0.3–1.2 mm, glabrescent, strigillose, or sericeous; blade usually ovate or oblong, rarely subrhombic, 4–13 × 3–7 mm, base asymmetric, one side usually angled and other side rounded, margins coarsely serrulate, apex acute, surfaces often with red spot in center, strigillose or sericeous, or adaxial surface glabrescent; 3-veined from base. |
usually alternate, occasionally opposite at proximalmost node; petiole 15–49 mm, glabrous; blade usually ovate, rarely oblong or elliptic, 13–54 × 7–38 mm, base usually rounded to broadly cuneate, rarely truncate, margins finely serrulate, apex obtuse, surfaces glabrous or with few scattered hairs; venation pinnate, midvein prominent. |
Involucre | obconic, 0.5–0.7 × 0.4–0.6 mm, strigillose; glands 4, yellow green to pink, circular to slightly oblong, 0.1–0.2 × 0.1–0.2 mm; appendages absent or white to pink, forming thin rim around edge of gland or oblong, 0.1–0.2 × 0.1–0.3 mm, distal margin entire or shallowly lobed. |
tubular or obconic, 1–1.7 × 0.7–1.4 mm, glabrous except for few hairs on lobes; involucral lobes divided into several linear, smooth lobes; glands 1(–3), greenish, sessile and broadly attached, 0.3–0.4 × 0.4–0.8 mm, opening oblong to subcircular, glabrous; appendages petaloid, white, elliptic, oblong, transversely oblong, or forming thin, lunate rim on gland margin, not incurved and covering glands, 0.3–0.9 × 0.6–1.3 mm, entire, undulate or slightly lobed, glabrous. |
Staminate flowers | 2–8. |
20–30. |
Pistillate flowers | ovary strigillose, often canescent when young; styles 0.1–0.3 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous; styles 0.6–1 mm, 2-fid 1/2 length. |
Capsules | ovoid, 1–1.2 × 1–1.3 mm, strigillose; columella 0.7–1.1 mm. |
oblate, 2.8–3.1 × 3.6–4.5 mm, glabrous; columella 1.9–2.4 mm. |
Seeds | orange-brown to pinkish, narrowly ovoid, 4-angled in cross section, 0.7–0.9(–1.1) × 0.5 mm, usually rugulose, with 3–6 faint, low, transverse ridges, rarely almost smooth. |
brown to blackish, ovoid, rounded in cross section, 1.9–2.4 × 1.5–1.8 mm, irregularly and coarsely tuberculate; caruncle absent or rudimentary. |
Cyathia | in dense, terminal, capitate glomerules, with reduced, bractlike leaves subtending cyathia; peduncles 0–0.8 mm. |
peduncle 0.9–3.5(–6.2) mm. |
Cyathial | arrangement: terminal dichasial branches 2, few-branched (weakly defined); pleiochasial bracts 2–3, opposite or whorled, wholly green, similar in shape and size to distal leaves; dichasial bracts smaller than distal leaves, often white at base. |
|
Euphorbia ophthalmica |
Euphorbia bifurcata |
|
Phenology | Flowering and fruiting year-round. | Flowering and fruiting summer–fall. |
Habitat | Hammock forests, disturbed areas in lawns, roadsides. | Riparian areas with cottonwoods and willows, pinyon pine woodlands, pine-oak forests, Douglas fir forests with pines. |
Elevation | 0–200 m. (0–700 ft.) | 1900–2300 m. (6200–7500 ft.) |
Distribution |
AR; CA; FL; GA; LA; MO; PA; Mexico; Central America; South America; West Indies [Introduced in Europe] |
NM; TX; Mexico; Central America (Guatemala) |
Discussion | Euphorbia ophthalmica is a weedy species distributed throughout the Neotropics. It is also adventive in the Old World. Whether it is indeed native to the southeastern United States is questionable; it is introduced in Arkansas, California, Missouri, and Pennsylvania and likely occurs also in other states. Although sometimes treated as E. hirta var. procumbens, E. ophthalmica appears sufficiently distinct to justify recognition at the rank of species, differing primarily by its mostly prostrate growth form, smaller leaves, and strictly terminal clusters of cyathia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia bifurcata is found in the mountains of southern New Mexico (Doña Ana, Grant, Lincoln, Otero, and Sierra counties) and trans-Pecos Texas (Brewster, Jeff Davis, and Presidio counties). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 280. | FNA vol. 12, p. 319. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Poinsettia |
Sibling taxa | ||
Synonyms | Chamaesyce ophthalmica, E. hirta var. procumbens, E. pilulifera var. procumbens | |
Name authority | Persoon: Syn. Pl. 2: 13. (1806) | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 190. (1859) |
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