Euphorbia heterophylla |
Euphorbia maculata |
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Mexican fireplant, painted euphorbia |
euphorbe maculée, milk purslane, milk spurge, prostrate spurge, sandmat, spotted sandmat, spotted sandmat or spurge, spotted 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. |
usually prostrate, occasionally with ascending tips, often mat-forming, not rooting at nodes, 5–45 cm, densely and evenly short-sericeous to sericeous or villous. |
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, linear-subulate, sometimes irregularly 2–3-lobed, 1–1.3 mm, sparsely short-sericeous to sericeous or villous; petiole 0.5–1.5 mm, moderately short-sericeous to sericeous or villous; blade oblong-ovate to ovate-elliptic or oblong-elliptic, 4–18 × 2.5–8 mm, base strongly asymmetric, one side usually angled and other ± truncate and expanded into small, rounded auricle, margins serrulate (longer side) or subentire (shorter side), apex rounded or broadly acute, abaxial surface pale grayish green, moderately to densely lanulose to villous, adaxial surface usually with irregular reddish streak along midvein, glabrate or with sparse, long, slender hairs; palmately veined at base, pinnate distally. |
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. |
obconic, 0.8–1 × 0.6–0.8 mm, sparsely strigose to short-sericeous; glands 4, green to yellow-green, turning pink with age, usually ± unequal, narrowly oblong to nearly linear, 0.1–0.2 × 0.2–0.5 mm; appendages white to reddish tinged, lunate to oblong, 0.1–0.3 × 0.2–1.5 mm, distal margin crenulate. |
Staminate flowers | 8–15. |
2–5. |
Pistillate flowers | ovary glabrous or puberulent; styles 0.8–1.3 mm, 2-fid 1/2 to nearly entire length. |
ovary sericeous; styles 0.3–0.4 mm, 2-fid at apex. |
Capsules | broadly ovoid, 2.8–3.8 × 4–5.3 mm, 3-lobed, usually glabrous, rarely sparsely puberulent; columella 2.1–2.8 mm. |
ovoid, well exserted from involucre at maturity, 1.3–1.5 × 1.2–1.4 mm, sparsely to moderately and evenly sericeous; columella 1–1.2 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. |
white to light brown, oblong-ovoid, sharply angular in cross section, 1–1.2 × 0.6–0.9 mm, with 3–4 low, transverse ridges that cross angles. |
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 or in small, cymose clusters at distal nodes or on congested, axillary branches; peduncle 0.1–0.6 mm. |
2n | = 28. |
= 28. |
Euphorbia heterophylla |
Euphorbia maculata |
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Phenology | Flowering and fruiting nearly year-round. | Flowering and fruiting spring–fall. |
Habitat | Disturbed areas, roadsides. | Disturbed areas, fallow fields, gardens, sidewalk cracks, railroads, roadsides. |
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; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; BC; NB; NS; ON; PE; QC; Mexico; Central America; South America; West Indies; Eurasia; Africa; Pacific Islands (New Zealand); 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.) |
Euphorbia maculata is a widespread weed in temperate latitudes, and it also occurs in cool climates at higher elevations in the tropics. It is presumed to be native to eastern and central North America, but given its extremely weedy tendencies, it is difficult to know for sure. It spreads readily in association with greenhouse plants and earth-moving activities, and it is notorious for its ability to colonize sidewalk cracks in the summer, even in congested cities. The name E. maculata was misapplied by most earlier botanists (for example, L. C. Wheeler 1941) to plants with ascending stems that are treated here as E. nutans. D. G. Burch (1966) reviewed the sources of data used by Linnaeus in his original description and concluded that the name E. maculata applies to this prostrate-stemmed taxon. For further discussion of the distinctions between E. maculata and the similar 47. E. humistrata, see the treatment of that species. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 323. | FNA vol. 12, p. 275. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | E. geniculata, Poinsettia geniculata, P. heterophylla | Chamaesyce maculata, C. mathewsii, C. supina, C. tracyi, E. supina |
Name authority | Linnaeus: Sp. Pl. 1: 453. (1753) | Linnaeus: Sp. Pl. 1: 455. (1753) |
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