Euphorbia heterophylla |
Euphorbia trichotoma |
|
---|---|---|
Mexican fireplant, painted euphorbia |
sand-dune spurge |
|
Habit | Herbs, annual, with taproot. | Herbs, perennial, with thick rootstock. |
Stems | erect-ascending, 20–100 cm, sparsely pilose to villous; branches ± straight. |
erect, branched, 15–40 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 absent; blade obovate to oblanceolate, 5–20 × 2–7 mm, base broadly attenuate, margins entire, apex acute to obtuse, surfaces glabrous; venation pinnate, very obscure, 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. |
hemispheric, 1–1.5 × 1.4–2 mm, glabrous; glands 5, elliptic to slightly crescent-shaped, 0.4–0.6 × 0.9–1.1 mm; horns divergent, 0.1–0.2 mm. |
Staminate flowers | 8–15. |
8–10. |
Pistillate flowers | ovary glabrous or puberulent; styles 0.8–1.3 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous; styles 0.2–0.4 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. |
depressed-ovoid, 1.1–1.5 × 2–3 mm, strongly 3-lobed; cocci rounded, minutely papillate, sometimes appearing smooth, glabrous; columella 1.6–1.9 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, ovoid-globose, 1.8–2 × 1.6–1.8 mm, smooth; caruncle ± rounded and flattened, 0.3 × 0.3 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, each usually 1–2 times 3-branched, sometimes unbranched; pleiochasial bracts similar in shape and size to distal leaves, alternate; dichasial bracts distinct, obovate to oblanceolate, base broadly attenuate, margins entire, apex acute to obtuse; axillary cymose branches 0. |
Cyathia | peduncle 0.9–1.5 mm. |
peduncle 0.7–1 mm. |
2n | = 28. |
|
Euphorbia heterophylla |
Euphorbia trichotoma |
|
Phenology | Flowering and fruiting nearly year-round. | Flowering and fruiting year-round (primarily spring–summer). |
Habitat | Disturbed areas, roadsides. | Coastal beaches, sand dunes, thickets. |
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]
|
FL; Mexico; Central America; West Indies |
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 trichotoma is found in coastal peninsular Florida from Hillsborough County south to Key West. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 323. | FNA vol. 12, p. 311. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | E. geniculata, Poinsettia geniculata, P. heterophylla | Galarhoeus trichotomus, Tithymalus trichotomus |
Name authority | Linnaeus: Sp. Pl. 1: 453. (1753) | Kunth: in A. von Humboldt et al., Nov. Gen. Sp. 2(fol.): 48; 2(qto.): 60. (1817) |
Web links |