Euphorbia dentata |
Euphorbia albomarginata |
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green poinsettia, tooth poinsettia, tooth spurge |
rattlesnake sandmat, rattlesnake weed, white-margin sandmat or sandwort, whitemargin sandmat |
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Habit | Herbs, annual, with taproot. | Herbs, perennial, with moderately to strongly thickened rootstock. |
Stems | erect or ascending, 15–60 cm, both pilose and inconspicuously strigillose; branches usually ± straight, occasionally proximal branches arcuate. |
prostrate, occasionally mat-forming, frequently rooting at nodes, 10–80 cm, glabrous. |
Leaves | usually opposite, occasionally alternate at distal nodes; petiole 5–20 mm, pilose; blade 30–70 × 4–35 mm, narrowly lanceolate to suborbiculate, usually broadest below middle, base usually acute to subobtuse, rarely subtruncate, margins coarsely crenate-dentate or doubly crenate, strigillose, flat to slightly revolute, apex broadly acute, abaxial surface long pilose with weak, filiform hairs, adaxial surface sparsely pilose to glabrate; venation pinnate, midvein prominent. |
opposite; stipules connate into conspicuous, deltate or ovate scale, white, 0.4–1(–2) mm, glabrous; petiole less than 1 mm, glabrous; blade ovate, oblong or orbiculate, 3–8(–15) × 3–7 mm, base strongly asymmetric, obtuse to hemicordate, margins whitish, entire, apex obtuse, rarely mucronulate, surfaces often with red blotch in center, glabrous; 3-veined from base but usually only midvein conspicuous. |
Involucre | campanulate, 3.8 × 1.8 mm, glabrous; involucral lobes divided into several linear, smooth lobes; glands (1–)2, green, sessile and broadly attached, 0.7–0.9 × 0.9–1.2 mm, opening oblong, glabrous; appendages absent. |
campanulate, 0.8–1.1 × 0.9–2 mm, glabrous; glands 4, greenish yellow to red, usually oblong to reniform, rarely subcircular, 0.2–0.5 × (0.2–)0.3–0.8 mm; appendages white to pink, flabellate to oblong, 0.3–1 × 0.6–1.3 mm, distal margin entire or crenulate to erose. |
Staminate flowers | 8–10. |
15–30. |
Pistillate flowers | ovary glabrous, styles 1.2 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous; styles 0.3–0.7 mm, 2-fid nearly entire length. |
Capsules | depressed-globose, 2.5–2.8 × 3.5–4 mm, 3-lobed, glabrous; columella 1.8–2.1 mm. |
broadly ovoid, 1.1–2.3 × 1.2–2 mm, glabrous; columella 1.1–1.6 mm. |
Seeds | pale gray to black, ovoid, rounded in cross section, 2.1–2.7 × 1.7–2.1 mm, evenly minute-tuberculate; caruncle 0.4–0.6 mm. |
white to gray or brownish red, oblong-ovoid, 4-angled in cross section, 1–1.7 × 0.5–0.8 mm, smooth. |
Cyathial | arrangement: terminal pleiochasial branches usually 3, occasionally reduced to congested cyme, 1–2-branched; pleiochasial bracts 2–4, often whorled, wholly green or paler green, white, or mauve at 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 0.7–1 mm. |
solitary at distal nodes; peduncle 1–4 mm. |
2n | = 28. |
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Euphorbia dentata |
Euphorbia albomarginata |
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Phenology | Flowering and fruiting spring–fall. | Flowering and fruiting year-round. |
Habitat | Bottomland forests, stream and river banks, bluffs, prairies, glades, fallow fields, roadsides, railroad cinders, open disturbed areas. | Disturbed areas in desert scrub, grasslands, mesquite woodlands, chaparral. |
Elevation | 0–1000 m. (0–3300 ft.) | 0–2300 m. (0–7500 ft.) |
Distribution |
AL; AR; GA; IA; IL; IN; KS; KY; LA; MD; MI; MO; MS; NC; NE; OH; OK; PA; SC; TN; TX; VA; WV; ON; Mexico (Chihuahua, Coahuila, Nuevo León, Tamaulipas)
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AZ; CA; CO; NM; NV; OK; TX; UT; Mexico [Introduced in Pacific Islands (Hawaii)]
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Discussion | Euphorbia dentata is native from northern Mexico and the south central United States north and east through the Ohio River Valley. Scattered occurrences in the southeastern United States likely represent adventive populations. Reports of E. dentata as a noxious weed (from the United States and the Old World) should most likely be attributed to introductions of E. davidii. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia albomarginata is native to northern and central Mexico and the southwestern and south-central United States. The species occurs in a variety of habitats in western North America and in some areas is quite weedy. It has been recorded as a waif in Louisiana. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 321. | FNA vol. 12, p. 259. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Poinsettia dentata | Chamaesyce albomarginata |
Name authority | Michaux: Fl. Bor.-Amer. 2: 211. (1803) | Torrey & A. Gray: in War Department [U.S.], Pacif. Railr. Rep. 2(4): 174. (1857) |
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