Euphorbia heterophylla |
Euphorbia deltoidea |
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Mexican fireplant, painted euphorbia |
wedge sandmat |
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Habit | Herbs, annual, with taproot. | Herbs, perennial, delicate, with woody, thickened taproot, 15 mm diam.. | ||||||||||||||||
Stems | erect-ascending, 20–100 cm, sparsely pilose to villous; branches ± straight. |
prostrate, ascending, or erect, often numerous and wiry, less than 0.1 mm diam., 5–20 cm, glabrous, puberulent, canescent, villous, or hirsute, shorter hairs often uncinate and longer hairs straight or irregularly twisted. |
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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 distinct, triangular, sometimes lacerate or ciliate, 0.2–0.3 mm, glabrous or hairy; petiole 0.3–1 mm, glabrous or hairy; blade narrowly to broadly deltate, cordate, or reniform, 2–5(–7) × 1–4.5(–5) mm, base asymmetric, cordate to rounded, margins entire, ± revolute, apex obtuse or rounded, surfaces glabrous or hairy; only midvein conspicuous. |
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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. |
turbinate to campanulate, 0.8–1 × 1.1–1.3 mm, glabrous or hairy; glands 4, green to yellow-green, oblong to subcircular, 0.2–0.4 × 0.4–0.6 mm; appendages absent or white, forming narrow rim at edge of gland, rarely slightly wider than gland, (0–)0.1(–0.3) × 0.4–0.6 mm, distal margin entire. |
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Staminate flowers | 8–15. |
8–14. |
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Pistillate flowers | ovary glabrous or puberulent; styles 0.8–1.3 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous or hairy, subtended by triangular pad of tissue; styles spreading, 0.3–0.4 mm, 2-fid 1/2 to nearly entire length. |
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Capsules | broadly ovoid, 2.8–3.8 × 4–5.3 mm, 3-lobed, usually glabrous, rarely sparsely puberulent; columella 2.1–2.8 mm. |
broadly deltoid, 1.2–1.5 × 2–2.2 mm, glabrous or hairy; columella 0.9–1.3 mm. |
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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. |
reddish brown, ovoid, 4-angled in cross section, 0.8–1.2 × 0.5–0.6 mm, obscurely wrinkled. |
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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. |
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Cyathia | peduncle 0.9–1.5 mm. |
solitary at distal nodes; peduncle 0.7–1.5 mm. |
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2n | = 28. |
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Euphorbia heterophylla |
Euphorbia deltoidea |
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Phenology | Flowering and fruiting nearly year-round. | |||||||||||||||||
Habitat | Disturbed areas, roadsides. | |||||||||||||||||
Elevation | 0–500 m. (0–1600 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 |
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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.) |
Subspecies 4 (4 in the flora). Euphorbia deltoidea comprises four narrowly endemic subspecies, all of which are endangered due to habitat loss and fragmentation. The subspecies occur in pine rockland habitat that is free of shrubby undergrowth. Periodic fires are required to keep the rockland habitat open. Subspecies serpyllum is restricted to Big Pine Key, Monroe County, whereas the other subspecies are found only in Miami-Dade County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 12, p. 323. | FNA vol. 12, p. 265. | ||||||||||||||||
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum | ||||||||||||||||
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Synonyms | E. geniculata, Poinsettia geniculata, P. heterophylla | Chamaesyce deltoidea | ||||||||||||||||
Name authority | Linnaeus: Sp. Pl. 1: 453. (1753) | Engelmann ex Chapman: Fl. South. U.S. ed. 2, 647. (1883) | ||||||||||||||||
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