Euphorbia davidii |
Euphorbia peplidion |
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David's poinsettia, David's spurge, tooth poinsettia, tooth spurge |
low spurge |
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Habit | Herbs, annual, with taproot. | Herbs, annual, with taproot. |
Stems | erect or ascending, 20–70 cm, both coarsely and sparsely hirsute and closely strigillose; branches usually ± straight, occasionally proximal branches arcuate. |
erect, unbranched or branched, 5–20 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. |
petiole 0–0.2 mm; blade linear-oblanceolate to cuneate-spatulate, 5–20 × 1–4 mm, base attenuate, margins entire, apex rounded to obtuse, surfaces glabrous; venation inconspicuously pinnate, midvein prominent. |
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-turbinate, 0.8–1 × 0.6–0.9 mm, glabrous; glands 4, elliptic, 0.2–0.3 × 0.5–0.6 mm; horns divergent, 0.4–0.5 mm. |
Staminate flowers | 5–8. |
5–10. |
Pistillate flowers | ovary glabrous or sparsely strigose; styles 1 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous; styles 0.5–0.7 mm, 2-fid. |
Capsules | broadly ovoid, 2.9–3.3 × 4–4.8 mm, 3-lobed, glabrous; columella 2.2–2.7 mm. |
depressed-globose, 1.8–2.3 × 2.6–3 mm, 3-lobed; cocci slightly flattened, without wings, smooth, glabrous; columella 1.3–1.5 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 to brown, oblong, 1.3–1.6 × 0.9–1.1 mm, abaxial faces irregularly large-pitted, adaxial faces longitudinally sulcate; caruncle flat, umbonate, 2-lobed, 0.4 × 0.7 mm. |
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. |
arrangement: terminal pleiochasial branches 3(–5), 1–3 times 2-branched; pleiochasial bracts linear, lanceolate, or spatulate, similar in size to distal leaves; dichasial bracts distinct, rhomboid-lanceolate to ovate, falcate, base rounded to obtuse, margins entire or slightly erose, apex acute; axillary cymose branches 0–3. |
Cyathia | peduncle 0.5–1 mm. |
peduncle 0.3–0.5 mm. |
2n | = 56. |
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Euphorbia davidii |
Euphorbia peplidion |
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Phenology | Flowering and fruiting summer–fall. | Flowering and fruiting late winter–spring. |
Habitat | Forests, stream and riverbanks, prairies, roadsides and open disturbed areas. | Dry, sandy areas, open areas with poor soils, roadsides, stream banks. |
Elevation | 200–1500 m. (700–4900 ft.) | 100–300 m. (300–1000 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 |
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 peplidion is native to central and south-central Texas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 320. | FNA vol. 12, p. 306. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | Tithymalus peplidion | |
Name authority | Subils: Kurtziana 17: 125, figs. 1, 2H–J. (1984) | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 191. (1859) |
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