Euphorbia ophthalmica |
Euphorbia bicolor |
|
---|---|---|
Florida hammock sandmat |
snow-on-the-prairie |
|
Habit | Herbs, usually annual, rarely short-lived perennial, with slender to slightly thickened taproot. | Herbs, annual, with taproot. |
Stems | usually prostrate, rarely ascending, 6–22 cm, usually both strigillose and hirsute. |
erect, unbranched or branched, 40–100 cm, pilose. |
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. |
alternate; stipules 0.3–0.4 mm; petiole 0.3–1 mm, pilose; blade narrowly elliptic to lanceolate, 37–54 × 7–17 mm, base cuneate to slightly rounded, margins entire, apex aristate or acute, surfaces pilose; venation obscure, only midvein conspicuous. |
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. |
campanulate, 2.7–3.5 × 2.2–3 mm, densely pilose; glands 4–5, green to pale greenish yellow, reniform, 0.6–0.7 × 1.4–1.6 mm; appendages white, obdeltate to orbiculate, 1.4–2.5 × 1.7–3 mm, dentate to erose. |
Staminate flowers | 2–8. |
30–70. |
Pistillate flowers | ovary strigillose, often canescent when young; styles 0.1–0.3 mm, 2-fid 1/2 to nearly entire length. |
ovary pilose; styles 0.7–1.2 mm, 2-fid 1/2 length. |
Capsules | ovoid, 1–1.2 × 1–1.3 mm, strigillose; columella 0.7–1.1 mm. |
depressed-ovoid, 3.5–7.5 × 6–8.7 mm, densely pilose; columella 4.5–5.5 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. |
tan to brown, ovoid, 4.3–4.5 × 3.7–3.9 mm, alveolate; caruncle absent. |
Cyathia | in dense, terminal, capitate glomerules, with reduced, bractlike leaves subtending cyathia; peduncles 0–0.8 mm. |
in terminal pleiochasia dichasial and pleiochasial bracts linear to narrowly oblanceolate, with conspicuous white margins; peduncle 1.2–3 mm, densely pilose. |
Euphorbia ophthalmica |
Euphorbia bicolor |
|
Phenology | Flowering and fruiting year-round. | Flowering and fruiting summer–fall. |
Habitat | Hammock forests, disturbed areas in lawns, roadsides. | Prairies, blackland (calcareous) prairies, pastures and clearings in former blackland prairie areas, roadside clearings. |
Elevation | 0–200 m. (0–700 ft.) | 100–200 m. (300–700 ft.) |
Distribution |
AR; CA; FL; GA; LA; MO; PA; Mexico; Central America; South America; West Indies [Introduced in Europe] |
AR; LA; OK; TX
|
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 bicolor is similar in appearance to E. marginata but can be distinguished by its linear to narrowly oblanceolate bracts and the presence of hairs on all parts of the plant. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 280. | FNA vol. 12, p. 243. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Alectoroctonum |
Sibling taxa | ||
Synonyms | Chamaesyce ophthalmica, E. hirta var. procumbens, E. pilulifera var. procumbens | |
Name authority | Persoon: Syn. Pl. 2: 13. (1806) | Engelmann & A. Gray: Boston J. Nat. Hist. 5: 233. (1845) |
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