Euphorbia exserta |
Euphorbia serpens |
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coastal sand spurge, maroon or purple sand spurge |
creeping spurge, Matted sandmat, Matted spurge, round-leafed spurge |
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Habit | Herbs, perennial, with spreading rootstock. | Herbs, annual, with slender taproot. |
Stems | erect or ascending, unbranched or branched, solitary, few, or occasionally densely clumped, previous year's dead stems not persistent, 20–33 cm, usually glabrous, rarely sparsely villous, glaucescent. |
prostrate, frequently mat-forming and rooting at nodes, 15–50 cm, glabrous. |
Leaves | alternate; stipules less than 0.1 mm; petiole (0–)1–3 mm, glabrous; blade linear or linear-elliptic to obovate or orbiculate, proximal greatly reduced, scalelike, 15–30 × 1–20 mm, base cuneate to rounded, margins entire, apex rounded, broadly acute, or emarginate, surfaces glabrous, glaucescent; venation often obscure on narrow leaves, midvein conspicuous. |
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. |
Involucre | usually dark red, campanulate, 1.3–1.6 × 1.4–2.1 mm, glabrous; glands 5, usually dark red, rarely greenish red, elliptic reniform, thickened, 0.3–0.5 × 0.8 mm; appendages white or green, often forming narrow rim around distal margin of gland, 0–0.2 mm, entire. |
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. |
Staminate flowers | 20–25. |
5–10. |
Pistillate flowers | ovary glabrous; styles 0.4–0.8 mm, 2-fid at apex. |
ovary glabrous; styles 0.2 mm, 2-fid 1/2 to nearly entire length. |
Capsules | depressed-globose, 1.8–2.5 × 3.6–4.4 mm, glabrous; columella 1.9–2.4 mm. |
broadly ovoid, oblate, or subglobose, 1.3–1.4 × 1.3–1.7 mm, glabrous; columella (0.9–)1–1.2 mm. |
Seeds | ashy white, ovoid, 2.1 × 1.3 mm, angled with 5 blunt longitudinal ridges, with shallow and irregular pits; caruncle absent. |
white to gray or light pink, ovoid, bluntly 3–4-angled in cross section, 0.7–1.1 × 0.4–0.7 mm, smooth. |
Cyathia | usually in terminal dichasia, sometimes pleiochasia; peduncle 6–33 mm, filiform, glabrous. |
solitary at distal nodes; peduncle 0.5–1(–2.5) mm. |
Euphorbia exserta |
Euphorbia serpens |
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Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting year-round (in warmer areas) or summer (in temperate regions). |
Habitat | Xeric to dry pine-oak scrub of sand hills, pine-oak woodlands, pine-oak savannas. | 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. |
Elevation | 0–150 m. (0–500 ft.) | 0–2000 m. (0–6600 ft.) |
Distribution |
FL; GA; NC; SC; VA
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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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Discussion | K. R. Park (1998) recognized both Euphorbia exserta and E. gracilior as distinct species, with the former known only from the holotype. However, this treatment follows M. J. Huft (1997) and treats E. gracilior as a synonym of E. exserta. Although the type of E. exserta is unusual in having greenish red (versus dark red) cyathia and glands, as well as small gland appendages, it is otherwise typical of the species as a whole, including features such as the upright habit, reddish coloration, scalelike proximal leaves, and filiform peduncles to 30 mm that are also common to plants formerly treated as E. gracilior. Euphorbia gracilis Elliott, which has sometimes been applied to E. exserta, is an illegitimate name (a later homonym of E. gracilis Loiseleur-Deslongchamps) and pertains here. The upright habit and usually dark red cyathia and glands distinguish Euphorbia exserta from the otherwise similar E. ipecacuanhae, while the glaucescent vegetative parts and smaller gland appendages readily separate E. exserta from the similar E. curtisii. Euphorbia exserta is found on the Gulf and Atlantic coastal plains. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 12, p. 246. | FNA vol. 12, p. 286. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Alectoroctonum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Tithymalopsis exserta, E. gracilior, T. gracilis | Chamaesyce serpens |
Name authority | (Small) Coker: Pl. Life Hartsville, 88. (1912) | Kunth: in A. von Humboldt et al., Nov. Gen. Sp. 2(fol.): 41; 2(qto.): 52. (1817) |
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