Euphorbia heterophylla |
Euphorbia strictior |
|
---|---|---|
Mexican fireplant, painted euphorbia |
panhandle spurge |
|
Habit | Herbs, annual, with taproot. | Herbs, perennial, with cylindric rootstock. |
Stems | erect-ascending, 20–100 cm, sparsely pilose to villous; branches ± straight. |
erect, branched, densely clumped, previous year’s dead stems often persistent, 30–70 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. |
alternate, persisting, spreading or ascending; stipules to 0.1 mm; petiole absent; blade linear to narrowly oblanceolate, (20–)40–70 × (2–)4–5 mm, base narrowly cuneate, margins entire, apex broadly acute, surfaces glabrous; venation obscure, only midvein conspicuous on wider leaves. |
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 or hemispheric, 1.2–2.4 × 2.2–3.2 mm, pilose; glands 5, green, broadly elliptic, 0.7–0.8 × 1.3–1.6 mm; appendages white, forming narrow rim around distal margin of gland, 0.2 × 1.5–1.8 mm, entire or erose. |
Staminate flowers | 8–15. |
20–25. |
Pistillate flowers | ovary glabrous or puberulent; styles 0.8–1.3 mm, 2-fid 1/2 to nearly entire length. |
ovary strigillose to tomentulose; styles 0.4–0.6 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. |
globose, all 3 locules fertile, 3.2–4.5 × 4–6.5 mm, sparsely strigillose; columella 2.5–3.9 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. |
gray-green to gray-brown, ovoid, 3.8 × 3 mm, shallowly and obscurely pitted; caruncle absent. |
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. |
in terminal dichasia; peduncle (2–)4–12(–18) mm proximal and mid peduncles and cyathia abscising early, sparsely to moderately strigose to sericeous. |
2n | = 28. |
|
Euphorbia heterophylla |
Euphorbia strictior |
|
Phenology | Flowering and fruiting nearly year-round. | Flowering and fruiting spring–fall. |
Habitat | Disturbed areas, roadsides. | Open grasslands and uplands. |
Elevation | 0–500 m. (0–1600 ft.) | 900–1400 m. (3000–4600 ft.) |
Distribution |
Mexico; Central America; South America [Introduced, Ala., Ariz., Calif., Fla., Ga., La., Miss., N.Mex., Tex.; introduced also in Eurasia, Africa]
|
NM; TX |
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 strictior is confined to a small area of the Texas Panhandle and adjacent New Mexico. The species is closely related to E. aaron-rossii and E. wrightii; it can be distinguished from E. wrightii by its larger stature, shorter and less petaloid involucral gland appendages, and early abscising proximal and mid cyathia and peduncles. Euphorbia strictior also tends to develop all three seeds in the capsule, whereas E. wrightii tends to develop only two. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 323. | FNA vol. 12, p. 251. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Alectoroctonum |
Sibling taxa | ||
Synonyms | E. geniculata, Poinsettia geniculata, P. heterophylla | |
Name authority | Linnaeus: Sp. Pl. 1: 453. (1753) | Holzinger: Contr. U.S. Natl. Herb. 1: 214, plate 18. (1892) |
Web links |