Euphorbia davidii |
Euphorbia lata |
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David's poinsettia, David's spurge, tooth poinsettia, tooth spurge |
broadleaf spurge, hoary sandmat |
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Habit | Herbs, annual, with taproot. | Herbs, perennial, with moderately thickened to robust rootstock. |
Stems | erect or ascending, 20–70 cm, both coarsely and sparsely hirsute and closely strigillose; branches usually ± straight, occasionally proximal branches arcuate. |
ascending to erect, or prostrate, 10–25 cm, strigose to short-sericeous or ± villous. |
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, 0.8–1.3 mm, strigose to short-sericeous or ± villous; petiole 0.5–2 mm, densely strigose to short-sericeous or ± villous; blade narrowly to broadly ovate-deltate, older ones often falcate, 4–12 × 3–7 mm, base asymmetric, obliquely rounded to obtuse, noticeably wider on one side, margins entire, often ± revolute, apex broadly acute, surfaces strigose to short-sericeous or ± villous; obscurely 3–5-veined from base, midvein prominent abaxially. |
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. |
broadly campanulate, 2–2.5 × 2.2–2.6, strigose; glands 4, greenish, oblong to semilunate, 0.2–0.7 × 0.6–1 mm; appendages rudimentary or white, forming narrow band, (0–)0.1–0.2 × (0–)0.6–1 mm, distal margin entire or crenate. |
Staminate flowers | 5–8. |
25–35. |
Pistillate flowers | ovary glabrous or sparsely strigose; styles 1 mm, 2-fid 1/2 to nearly entire length. |
ovary densely strigose to short-sericeous or ± villous; styles dark purplish, 0.8–1.2 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. |
ovoid, 1.9–2.3 × 2–2.4 mm, strigose to short-sericeous or ± villous; columella 1.7–2.2 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. |
whitish, oblong, 4-angled in cross section, faces concave, 1.5–1.8(–2) × 0.6–0.9 mm, smooth. |
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; peduncle 1–3 mm. |
2n | = 56. |
= 28, 56. |
Euphorbia davidii |
Euphorbia lata |
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Phenology | Flowering and fruiting summer–fall. | Flowering and fruiting spring–fall. |
Habitat | Forests, stream and riverbanks, prairies, roadsides and open disturbed areas. | Mountain slopes, canyons, basins, rocky prairies, roadsides, disturbed sites, usually in calcareous soils, sometimes in igneous-derived, sandy or rocky soils. |
Elevation | 200–1500 m. (700–4900 ft.) | 600–2200 m. (2000–7200 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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CO; KS; NM; OK; TX; Mexico (Chihuahua, Coahuila)
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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.) |
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Source | FNA vol. 12, p. 320. | FNA vol. 12, p. 275. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | E. dilatata, Chamaesyce lata, E. rinconis | |
Name authority | Subils: Kurtziana 17: 125, figs. 1, 2H–J. (1984) | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 188. (1859) |
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