Euphorbia polygonifolia |
Euphorbia micromera |
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dune spurge, euphorbe à feuilles de renouée, seaside sandmat, seaside spurge |
desert spurge, Sonoran sandmat, tiny sandmat |
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Habit | Herbs, annual, with taproot. | Herbs, annual, with slender taproot. |
Stems | usually prostrate, occasionally ascending, 5–30 cm, glabrous. |
prostrate, mat-forming, 5–35 cm, glabrous or shortly pilose. |
Leaves | opposite; stipules usually distinct, occasionally connate basally (distal portion of stem), triangular-subulate, entire or divided, 0.8–1.5 mm, glabrous; petiole 1–3 mm, glabrous; blade oblong, linear-oblong, or linear-lanceolate, 5–16 × 2–4 mm, base slightly asymmetric, obtuse or subcordate, margins entire, apex obtuse, often mucronulate, surfaces uniformly green or reddish tinged, glabrous; venation obscure. |
opposite; stipules distinct, subulate, 0.2–0.4 mm, pilose; petiole 0.5–1.2 mm, glabrous or pilose; blade ovate to elliptic, 6–15 × 2–4 mm, base asymmetric, one side cuneate to rounded, other side rounded, margins entire, apex obtuse, surfaces glabrous or pilose; venation obscure or only midvein conspicuous. |
Involucre | obconic-campanulate, 1.2–1.7 × 1–1.4 mm, glabrous; glands 4, occasionally rudimentary, green-yellow to tan or orange-tinged, occasionally shortly stipitate, usually broadly oval to subcircular, sometimes figure eight-shaped, shallowly cupped, 0.1–0.3 × 0.2–0.4 mm; appendages absent or rudimentary. |
campanulate, 0.4–0.6 × 0.5–0.9 mm, glabrous or pilose; glands 4, red, circular to oblong, 0.1 × 0.1–0.2 mm; appendages absent. |
Staminate flowers | 5–14. |
2–5. |
Pistillate flowers | ovary glabrous; styles 0.7–1 mm, 2-fid 1/2 length. |
ovary usually glabrous, rarely pilose; styles 0.1–0.2 mm, 2-fid at apex. |
Capsules | broadly ovoid, 3–3.5(–4) × (2–)2.4–3 mm, glabrous; columella 2–3 mm. |
oblong, 1.3–1.5 × 1.1–1.3 mm, usually glabrous, rarely pilose; columella 1–1.2 mm. |
Seeds | ashy white, wedge-shaped to slightly ovoid, weakly dorsiventrally compressed and elliptic-terete to bluntly subangled in cross section, back strongly rounded, face slightly rounded, (2–)2.2–2.8 × 1.6–1.9 mm, smooth or minutely pitted, with smooth brown line from top to bottom on adaxial side. |
light gray, narrowly ovoid, 4-angled in cross section, 0.9–1 × 0.5–0.6 mm, smooth to slightly rugose or with 1–4 faint transverse ridges that do not pass through abaxial keel. |
Cyathia | solitary or in small, cymose clusters at distal nodes; peduncle 0.5–5 mm. |
solitary at distal nodes; peduncle 0.4–1.4 mm. |
Euphorbia polygonifolia |
Euphorbia micromera |
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Phenology | Flowering and fruiting early summer–fall. | Flowering nearly year-round in response to sufficient rainfall. |
Habitat | Sandy maritime and freshwater beaches and foredunes. | Desert scrub, riparian woods with ash and willow, saltbush scrub, Joshua tree woodlands and grasslands, often in sandy or gravelly areas. |
Elevation | 0–200 m. (0–700 ft.) | -20–1800 m. (-100–5900 ft.) |
Distribution |
CT; DE; FL; GA; IL; IN; MA; MD; ME; MI; NC; NH; NJ; NY; OH; PA; RI; SC; VA; WI; NB; NS; ON; PE; QC
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AZ; CA; NM; NV; TX; UT; Mexico (Baja California, Baja California Sur, Chihuahua, Coahuila, Durango, Sonora)
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Discussion | Euphorbia polygonifolia is native to coastal beaches and dunes along the Atlantic Ocean from the maritime provinces of Canada south to northern Florida. The species also occurs disjunctly along the shores of the North American Great Lakes. Euphorbia polygonifolia was native to Quebec but is now considered extirpated from the province. It has apparently been introduced in Europe, but it is unclear if it has persisted there (L. C. Wheeler 1941). Immature individuals of this species can be somewhat difficult to distinguish from E. bombensis where their ranges overlap (Virginia to northern Florida). Where they occur together, E. polygonifolia tends to be a pioneer species on the upper beach and foredune front, whereas E. bombensis tends to inhabit areas behind the foredune (R. D. Porcher and D. A. Rayner 2002). Euphorbia polygonifolia can be distinguished also by its larger capsules and larger, wedge-shaped to slightly ovoid seeds. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 12, p. 284. | FNA vol. 12, p. 278. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Chamaesyce polygonifolia | Chamaesyce micromera |
Name authority | Linnaeus: Sp. Pl. 1: 455. (1753) | Boissier: Proc. Amer. Acad. Arts 5: 171. (1861) |
Web links |