Euphorbia serpens |
Euphorbia exigua |
|
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creeping spurge, Matted sandmat, Matted spurge, round-leafed spurge |
dwarf spurge, small spurge |
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Habit | Herbs, annual, with slender taproot. | Herbs, annual, with taproot. |
Stems | prostrate, frequently mat-forming and rooting at nodes, 15–50 cm, glabrous. |
erect, unbranched or branched, 3–30 cm, glabrous. |
Leaves | opposite; stipules connate into conspicuous, deltate scale, white to pink, membranaceous, 0.5–1(–1.2) mm, glabrous; petiole less than 1 mm, glabrous; blade ovate, oblong or orbiculate, 2–7(–9) × 2–6 mm, base asymmetric, rounded to subcordate, margins entire, apex rounded, surfaces without red blotch, glabrous; usually only midvein conspicuous. |
petiole 0–0.5 mm; blade linear, linear-oblong, or linear-spatulate, 2–30 × 1–5 mm, base cuneate or truncate, margins entire, apex acute, obtuse, or emarginate, surfaces glabrous; venation inconspicuous, only midvein prominent. |
Involucre | campanulate to turbinate, 0.3–0.7(–1) × 0.4–0.6 mm, glabrous; glands 4, yellow, oblong, 0.1 × 0.2 mm; appendages white to pinkish, equal, forming narrow rim at edge of gland, 0.1–0.2 × 0.2–0.3 mm, distal margin entire or crenulate. |
cupulate, 0.3–0.5 × 0.6–0.8 mm, glabrous; glands 4, elliptic to crescent-shaped, 0.2–0.4 × 0.3–0.6 mm; horns divergent, 0.2–0.5 mm. |
Staminate flowers | 5–10. |
5–8. |
Pistillate flowers | ovary glabrous; styles 0.2 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous; styles 0.5–0.7 mm, 2-fid. |
Capsules | broadly ovoid, oblate, or subglobose, 1.3–1.4 × 1.3–1.7 mm, glabrous; columella (0.9–)1–1.2 mm. |
subglobose, 1–1.8 × 1.3–2 mm, slightly lobed; cocci rounded, smooth, puncticulate toward abaxial line, glabrous; columella 1.1–1.4 mm. |
Seeds | white to gray or light pink, ovoid, bluntly 3–4-angled in cross section, 0.7–1.1 × 0.4–0.7 mm, smooth. |
blackish to grayish, 4-angled-ovoid, 1–1.5 × 0.5–0.7 mm, white, tuberculate; caruncle conic or subconic, 0.1–0.3 × 0.1–0.3 mm. |
Cyathia | solitary at distal nodes; peduncle 0.5–1(–2.5) mm. |
peduncle 0–2 mm. |
Cyathial | arrangement: terminal pleiochasial branches 3–5, each 1–3 times 2-branched; pleiochasial bracts similar in shape and size to or sometimes slightly longer and wider than distal leaves; dichasial bracts distinct, linear, or linear-lanceolate, or lanceolate-ovate, base rounded to subcordate, margins entire, apex acute; axillary cymose branches 0–5. |
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Euphorbia serpens |
Euphorbia exigua |
|
Phenology | Flowering and fruiting year-round (in warmer areas) or summer (in temperate regions). | Flowering and fruiting summer–fall. |
Habitat | Mostly sandy or well-drained soils, desert scrub, coastal scrub, chaparral, oak and juniper woodlands, sand dunes, riparian forests, mesquite grasslands, prairies, coniferous and deciduous hardwood forests, disturbed areas. | Edges of gardens, roadsides, waste places. |
Elevation | 0–2000 m. (0–6600 ft.) | 0–1500 m. (0–4900 ft.) |
Distribution |
AL; AR; AZ; CA; CO; FL; GA; IA; IL; IN; KS; KY; LA; MI; MO; MS; MT; ND; NE; NJ; NM; OH; OK; PA; SD; TN; TX; UT; VT; WY; ON; SK; Mexico; Central America; South America; West Indies; Bermuda [Introduced in Europe, Asia, Africa, Australia]
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CA; NY; WV; BC; NS; ON; Europe; w Asia; n Africa; Atlantic Islands (Macaronesia) [Introduced in North America] |
Discussion | Euphorbia serpens is one of the most widespread species of the genus in the New World. While it may be indigenous to a portion of the flora area, probably in the warmer, southern part of its range, it is weedy and has likely been introduced in many parts of the flora area, such as Canada and the eastern United States. It is also widely distributed in the Old World, where it is certainly introduced. The strictly prostrate habit with stems rooting at the nodes is characteristic. Euphorbia serpens is often confused with E. albomarginata, a species distributed in the southwestern United States; in addition to the features mentioned in the key, an easy and reliable way to distinguish between them is by the size of the involucral gland appendages: those of E. albomarginata are conspicuous to the naked eye, whereas those of E. serpens are inconspicuous. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia exigua can be easily distinguished from other annual species of the genus in the flora area by its tuberculate seeds. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 286. | FNA vol. 12, p. 302. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | Chamaesyce serpens | Tithymalus exiguus |
Name authority | Kunth: in A. von Humboldt et al., Nov. Gen. Sp. 2(fol.): 41; 2(qto.): 52. (1817) | Linnaeus: Sp. Pl. 1: 456. (1753) |
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