Euphorbia heterophylla |
Euphorbia mesembrianthemifolia |
|
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Mexican fireplant, painted euphorbia |
coastal beach sandmat |
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Habit | Herbs, annual, with taproot. | Subshrubs or shrubs, perennial, with thickened and often woody rootstock. |
Stems | erect-ascending, 20–100 cm, sparsely pilose to villous; branches ± straight. |
erect to ascending, or nearly decumbent in shifting sand, 25–60 cm, glabrous. |
Leaves | usually alternate, occasionally opposite proximally; petiole 10–50 mm, pilose; blade narrowly lanceolate to elliptic or broadly obovate (then usually pandurate and 4-lobed), often polymorphic on single plants, 30–200 × 20–140 mm, base acute, margins sparsely glandular-serrulate, hirtellous, flat, apex acute to obtuse, abaxial surface sparsely appressed-pilose, adaxial surface sparsely pilosulous to glabrate; venation pinnate, midvein prominent. |
opposite; stipules connate, forming conspicuous, ligulate or deltate scale, short cleft or fringed, 1–1.8 mm, glabrous; petiole 0.5–1 mm, glabrous; blade ovate to elliptic often folded along midrib, 5–12 × 3–8 mm, ± fleshy, base slightly asymmetric, truncate to cordate, partially obscuring stem, margins entire, apex usually obtuse, rarely acute, surfaces yellowish to dark green, glabrous glaucous; obscurely 3–5-veined at base, pinnate distally, only midvein conspicuous. |
Involucre | usually campanulate, occasionally nearly hemispheric, 1.5–1.9 × 1.2–1.8 mm, glabrous; involucral lobes divided into several linear, smooth lobes; gland 1, yellow-green, stipitate, clavate, 1–1.4 × 1–1.2 mm, opening circular (occasionally flattened from pressing), with annular rim, glabrous; appendages absent. |
campanulate, 1–1.6 × 0.7–1.2 mm, glabrous; glands 4, brown, usually elliptic, occasionally almost round, 0.2–0.4 × 0.5–0.7 mm, fleshy; appendages white, oblong, rarely rudimentary, 0.2–0.4 × 0.5–0.9 mm, distal margin entire or undulate. |
Staminate flowers | 8–15. |
12–20. |
Pistillate flowers | ovary glabrous or puberulent; styles 0.8–1.3 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous; styles 0.3–0.4 mm, 2-fid 1/2 length. |
Capsules | broadly ovoid, 2.8–3.8 × 4–5.3 mm, 3-lobed, usually glabrous, rarely sparsely puberulent; columella 2.1–2.8 mm. |
subglobose subtended by calyxlike structure, 1.5–2 × 2.2–2.8 mm, glabrous; columella 1–1.5 mm. |
Seeds | brown-gray to ashy gray, broadly deltoid, 2.4–2.8 × 1.9–2.4 mm, angular in cross section, dorsal face strongly acute-carinate, tuberculate, with broad rounded tubercles in 2 rows; caruncle 0.1 mm. |
ashen, broadly ovoid, angled in cross section, faces plump, convex, 1.2–1.3 × 0.9–1.2 mm, obscurely pitted. |
Cyathial | arrangement: terminal dichasial branches usually 2, occasionally reduced to congested cyme, 1–2-branched (often congested and difficult to discern); pleiochasial bracts 2–4, often whorled, wholly green or paler green at base, similar in shape and size to distal leaves; dichasial bracts highly reduced, rarely absent in highly congested clusters. |
|
Cyathia | peduncle 0.9–1.5 mm. |
solitary at distal nodes; peduncle 0.5–1 mm. |
2n | = 28. |
|
Euphorbia heterophylla |
Euphorbia mesembrianthemifolia |
|
Phenology | Flowering and fruiting nearly year-round. | Flowering and fruiting year-round. |
Habitat | Disturbed areas, roadsides. | Sandy and rocky shores, associated beach scrub. |
Elevation | 0–500 m. (0–1600 ft.) | 0–10 m. (0–0 ft.) |
Distribution |
Mexico; Central America; South America [Introduced, Ala., Ariz., Calif., Fla., Ga., La., Miss., N.Mex., Tex.; introduced also in Eurasia, Africa]
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FL; Mexico; West Indies; Bermuda; South America (Colombia, Venezuela) |
Discussion | Euphorbia heterophylla occurs from the southern United States, where it is likely naturalized, south through Mexico and Central America to South America. Because of its weediness, the precise native range in tropical and subtropical parts of the New World is not well understood. It has become widely established also in warm areas of the Old World. Leaf shape in this species is highly polymorphic within both populations and individuals. Euphorbia heterophylla can appear superficially similar to E. cyathophora but differs in its stipitate, circular involucral glands and its floral bracts that are at most very pale at the base (never colored as is typical in E. cyathophora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia mesembrianthemifolia is found in the flora area along the sandy and rocky shores of southern Florida from Pinellas and Volusia counties southward. It is one of the few members of subg. Chamaesyce in the flora area that is a shrub or subshrub. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 323. | FNA vol. 12, p. 277. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | E. geniculata, Poinsettia geniculata, P. heterophylla | Chamaesyce buxifolia, C. mesembrianthemifolia, E. buxifolia |
Name authority | Linnaeus: Sp. Pl. 1: 453. (1753) | Jacquin: Enum. Syst. Pl., 22. (1760) |
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