Euphorbia heterophylla |
Euphorbia peplus |
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Mexican fireplant, painted euphorbia |
petty spurge |
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Habit | Herbs, annual, with taproot. | Herbs, annual, with taproot. |
Stems | erect-ascending, 20–100 cm, sparsely pilose to villous; branches ± straight. |
erect, unbranched or branched, 5–30 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. |
petiole 1–10 mm; blade obovate, oblong, or suborbiculate, 5–25 × 4–15 mm, base attenuate or cuneate, margins entire, apex obtuse, surfaces glabrous; venation pinnate, midvein prominent. |
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. |
cupulate to slightly turbinate, 0.6–1.1 × 0.7–0.9 mm, glabrous; glands 4, elliptic, 0.2–0.3 × 0.5–0.6 mm; horns slightly convergent to divergent, 0.4–0.6 mm. |
Staminate flowers | 8–15. |
10–15. |
Pistillate flowers | ovary glabrous or puberulent; styles 0.8–1.3 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous; styles 0.1–0.2 mm, 2-fid. |
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, 1.3–2 × 1.5–2.2 mm, slightly 3-lobed; cocci rounded, with 2 low longitudinal wings, smooth, glabrous; columella 1.1–1.3 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. |
whitish or grayish, subovoid, 1–1.6 × 0.6–1 mm, abaxial faces regularly large-pitted (appearing almost alveolate), adaxial faces longitudinally sulcate; caruncle deciduous, conic, 0.2–0.5 × 0.2–0.7 mm. |
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. |
arrangement: terminal pleiochasial branches 3–5, usually 2–8 times 2-branched, 1st branching level rarely 3-furcate; pleiochasial bracts similar in shape to and slightly larger than distal leaves; dichasial bracts distinct, ovate to obovate, base obtuse, margins entire, apex obtuse, usually mucronate; axillary cymose branches 0–3. |
Cyathia | peduncle 0.9–1.5 mm. |
peduncle 0.4–1.1 mm. |
2n | = 28. |
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Euphorbia heterophylla |
Euphorbia peplus |
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Phenology | Flowering and fruiting nearly year-round. | Flowering and fruiting year-round. |
Habitat | Disturbed areas, roadsides. | Edges of gardens, weedy flower beds, roadsides, waste places, open ground near forests. |
Elevation | 0–500 m. (0–1600 ft.) | 0–1500 m. (0–4900 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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AL; AZ; CA; CO; CT; DE; IA; ID; IL; IN; KY; LA; MA; MD; ME; MI; MT; NC; ND; NH; NJ; NM; NV; NY; OH; OR; PA; RI; TN; TX; UT; VA; VT; WA; WI; WV; AB; BC; MB; NB; NF; NS; ON; PE; QC; SK; Europe; w Asia [Introduced in North America; introduced also in Mexico, West Indies, Bermuda, Central America, South America, Africa, Atlantic Islands, Indian Ocean Islands, Pacific Islands, Australia]
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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.) |
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Source | FNA vol. 12, p. 323. | FNA vol. 12, p. 307. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | E. geniculata, Poinsettia geniculata, P. heterophylla | Esula peplus, Galarhoeus peplus, Tithymalus peplus |
Name authority | Linnaeus: Sp. Pl. 1: 453. (1753) | Linnaeus: Sp. Pl. 1: 456. (1753) |
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