Euphorbia davidii |
Euphorbia villifera |
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David's poinsettia, David's spurge, tooth poinsettia, tooth spurge |
hairy spurge |
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Habit | Herbs, annual, with taproot. | Herbs, annual or perennial, with slender taproot or thickened, woody rootstock. |
Stems | erect or ascending, 20–70 cm, both coarsely and sparsely hirsute and closely strigillose; branches usually ± straight, occasionally proximal branches arcuate. |
usually erect to ascending, rarely prostrate to decumbent, 10–30 cm, papillate, usually villous, sometimes glabrous. |
Leaves | usually opposite, occasionally alternate at distal nodes; petiole 7–25 mm, strigose; blade usually narrowly to broadly elliptic, occasionally lance-elliptic, 10–100 × 5–35 mm, base cuneate to attenuate, margins coarsely crenate-dentate, strigose, revolute to nearly flat, apex broadly acute to acuminate, or obtuse, abaxial surface strigose with stiff, strongly tapered hairs, adaxial surface sparsely strigose-hirsute; venation pinnate, midvein prominent. |
opposite; stipules distinct, filiform, usually undivided, rarely divided into 2–3 segments), 0.3–0.7 mm, glabrous, papillate; petiole 0.6–1.8 mm, usually villous, rarely glabrous; blade ovate, 3–12 × 2–10 mm, base asymmetric, rounded to slightly cordate, margins entire or serrulate, apex acute to obtuse, surfaces usually villous, rarely glabrous; only midvein conspicuous. |
Involucre | cylindric, 2.5–3 × 1.3–1.8 mm, glabrous; involucral lobes divided into 5–7 linear, papillate lobes; gland 1, yellow-green, sessile and broadly attached, 0.9 × 1.3 mm, opening oblong, glabrous; appendages absent. |
campanulate, 0.7–0.9 × 0.6–1 mm, glabrous or pilose; glands 4, pink, oval, oblong, or trapezoidal, 0.1–0.2 × 0.2 mm; appendages white to pink, flabellate, oblong, ovate, or nearly rectangular, 0.2–0.4 × 0.2–0.6 mm, distal margin entire. |
Staminate flowers | 5–8. |
10–25. |
Pistillate flowers | ovary glabrous or sparsely strigose; styles 1 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous; styles 0.3–0.5 mm, 2-fid 1/2 to nearly entire length. |
Capsules | broadly ovoid, 2.9–3.3 × 4–4.8 mm, 3-lobed, glabrous; columella 2.2–2.7 mm. |
oblate-deltoid, cocci often elongated and terminating in an empty portion, 1.5–2 × 2.1–3.1 mm, glabrous; columella 0.9–1.5 mm. |
Seeds | black to brown or pale gray, ovoid to triangular-ovoid, angular in cross section, 2.4–2.9 × 2.2–2.9 mm, low-tuberculate, tubercles irregularly arranged or in faint, transverse row; caruncle 0.9–1.1 mm. |
gray-brown to red-brown, ovoid-oblong, weakly 4-angled in cross section, 1–1.4 × 0.6–0.8 mm, smooth, faintly rugose, or with inconspicuous transverse ridges. |
Cyathial | arrangement: terminal pleiochasial branches usually 3, occasionally reduced to congested cyme, 1–2-branched; pleiochasial bracts 2–4, often whorled, green with diffuse greenish white to mauve near base, similar in shape and size to distal leaves or slightly narrower; dichasial bracts similar in shape to distal leaves but smaller, often highly reduced. |
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Cyathia | peduncle 0.5–1 mm. |
solitary at distal nodes; peduncles 0–1.8 mm. |
2n | = 56. |
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Euphorbia davidii |
Euphorbia villifera |
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Phenology | Flowering and fruiting summer–fall. | Flowering and fruiting early spring–early winter. |
Habitat | Forests, stream and riverbanks, prairies, roadsides and open disturbed areas. | Riparian forests with walnuts and sycamores, juniper woodlands, pine-oak woodlands, mostly on limestone substrates. |
Elevation | 200–1500 m. (700–4900 ft.) | 100–1400 m. (300–4600 ft.) |
Distribution |
AR; AZ; CA; CO; FL; IA; ID; IL; IN; KS; KY; LA; MA; MI; MN; MO; NC; NE; NJ; NM; NY; OH; OK; SD; TN; TX; UT; VA; VT; WI; WV; WY; ON; QC; Mexico (Chihuahua, Coahuila, Sonora) [Introduced in South America, Eurasia (China, Russia), Australia]
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TX; Mexico; Central America |
Discussion | Euphorbia davidii is native from the southwestern United States and northern Mexico north through the southern Great Plains; it apparently is adventive elsewhere. The species is the weediest member of the E. dentata species group (following M. H. Mayfield 1997) and has become an agricultural weed in North America, South America (for example, Argentina), and in the Old World (particularly Australia and Russia). Euphorbia davidii can be distinguished from the closely similar E. dentata by its larger capsules and seeds, often more elliptic leaves, and shorter, stiffer hairs. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Although Euphorbia villifera has been reported from New Mexico (W. C. Martin and C. R. Hutchins 1980), no vouchers to verify its presence there were located. In Texas, E. villifera is known from the Edwards Plateau westward into the trans-Pecos region. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 320. | FNA vol. 12, p. 293. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Chamaesyce stanfieldii, C. villifera, E. stanfieldii, E. villifera var. nuda | |
Name authority | Subils: Kurtziana 17: 125, figs. 1, 2H–J. (1984) | Scheele: Linnaea 22: 153. (1849) |
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