Euphorbia davidii |
Euphorbia blodgettii |
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David's poinsettia, David's spurge, tooth poinsettia, tooth spurge |
limestone sandmat |
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Habit | Herbs, annual, with taproot. | Herbs, usually annual, occasionally perennial, with slender to slightly thickened taproot, 3.5 mm diam.. |
Stems | erect or ascending, 20–70 cm, both coarsely and sparsely hirsute and closely strigillose; branches usually ± straight, occasionally proximal branches arcuate. |
prostrate to decumbent, loosely mat-forming, often rooting at nodes, 10–45 cm, 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, subulate filiform segments (lower side), or connate forming conspicuous, broad deltate scale (upper side), toothed, 0.5–1 mm, glabrous; petiole 0.7–1 mm, glabrous; blade ovate to oblong-elliptic, 4–10 × 2–5 mm, base asymmetric, subcordate to rounded, margins usually entire, occasionally toothed, apex usually obtuse to rounded, occasionally acute to apiculate, surfaces without red blotch, glabrous; 3-veined from base, 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. |
turbinate to campanulate, 0.5–0.6 × 0.4–0.6 mm, glabrous; glands 4, red, slightly concave, elliptic-oblong, 0.1 × 0.1–0.3 mm; appendages white to pink, unequal, pair near sinus lunate to oblong, 0.1–0.2 × 0.1–0.3 mm, distal margin entire, crenulate, or irregularly sinuate, other pair sometimes rudimentary, 0–0.1 × 0.1–0.3 mm, distal margin crenulate or entire. |
Staminate flowers | 5–8. |
8–12. |
Pistillate flowers | ovary glabrous or sparsely strigose; styles 1 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous; styles 0.3–0.4 mm, 2-fid 1/2 length. |
Capsules | broadly ovoid, 2.9–3.3 × 4–4.8 mm, 3-lobed, glabrous; columella 2.2–2.7 mm. |
broadly ovoid, 1.2–1.7 × 1.4–1.9 mm, glabrous; columella 1.2–1.6 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 to reddish brown, oblong-ovoid, 4-angled in cross section, 0.9–1.1 × 0.5–0.6 mm, flat or obscurely wrinkled. |
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 or in small, cymose clusters at distal nodes of stem or on congested, axillary branches; peduncle 0.4–0.6 mm. |
2n | = 56. |
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Euphorbia davidii |
Euphorbia blodgettii |
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Phenology | Flowering and fruiting summer–fall. | Flowering and fruiting year-round. |
Habitat | Forests, stream and riverbanks, prairies, roadsides and open disturbed areas. | Coastal sand dunes and disturbed upland sandy areas. |
Elevation | 200–1500 m. (700–4900 ft.) | 0–20 m. (0–100 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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FL |
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.) |
Euphorbia blodgettii is found only in peninsular Florida. It is closely related to E. garberi, E. porteriana, and E. serpens (Y. Yang and P. E. Berry 2011). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 320. | FNA vol. 12, p. 261. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Chamaesyce blodgettii, C. nashii | |
Name authority | Subils: Kurtziana 17: 125, figs. 1, 2H–J. (1984) | Engelmann ex Hitchcock: Rep. (Annual) Missouri Bot. Gard. 4: 126, plate 13. (1893) |
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