Euphorbia setiloba |
Euphorbia bombensis |
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fringe spurge, shaggy spurge, Yuma sandmat |
Dixie sandmat, southern seaside spurge |
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Habit | Herbs, annual, with slender taproot. | Herbs, usually annual, rarely perennial, with taproot. |
Stems | prostrate, mat-forming, 5–50 cm, villous with glistening glandular hairs. |
prostrate or slightly ascending, 10–40 cm, glabrous. |
Leaves | opposite; stipules distinct, filiform, rudimentary to 0.2 mm, glabrous or sparsely villous with glistening glandular hairs; petiole 0.5–1.5 mm, villous; blade oblong, ovate, or elliptic, 3–7 × 2–4 mm, base asymmetric, rounded, margins entire, apex obtuse, surfaces villous; weakly 3-veined from base, commonly only midvein conspicuous. |
opposite; stipules distinct, linear-subulate, usually divided into 3 linear segments, 1–2 mm, glabrous; petiole 1–2 mm, glabrous; blade oblong or elliptic-oblong, 4–15 × 2–3 mm, base asymmetric to nearly symmetric, obtuse, margins entire, apex acute to mucronate, surfaces green to reddish flushed, glabrous; only midvein conspicuous. |
Involucre | campanulate or urceolate, 0.7–1 × 0.5–0.8 mm, villous; glands 4, red to pink, oblong to slightly reniform, 0.1–0.2 × 0.2–0.3 mm; appendages white to pink, deeply incised into 3–6 triangular to subulate, attenuate, acute segments, 0.3–0.6 × 0.6–1 mm, segments entire. |
obconic-campanulate, 1.2–1.6 × 1.5–1.7 mm, glabrous; glands 4, green to red, slightly concave, elliptic, oblong, or subcircular, 0.3–0.5 × 0.4–0.6 mm; appendages white or pink, semilunate, fringing edge of gland, sometimes rudimentary, (0–)0.1–0.5(–0.7) × 0.5–0.8 mm, distal margin crenate to entire. |
Staminate flowers | 3–7. |
5–16. |
Pistillate flowers | ovary villous; styles 0.3–0.4 mm, 2-fid 1/2 length. |
ovary glabrous; styles 0.2–0.3 mm, 2-fid 1/2 length. |
Capsules | subglobose to ovoid, 1–1.2 mm diam., villous; columella 0.9–1.1 mm. |
broadly ovoid, 2–2.1 × 2.3–2.5 mm, glabrous; columella 1.5–2 mm. |
Seeds | pink to light gray, narrowly ovoid, 4-angled in cross section, 0.8–1 × 0.5–0.6 mm, dimpled or with faint transverse ridges that do not pass through abaxial keel. |
ashy white, plumply ovoid, terete to bluntly subangled in cross section, 1.5–1.9 × 1–1.2 mm, smooth or minutely pitted, with smooth brown line from top to bottom on adaxial side. |
Cyathia | solitary at distal nodes, nodes often congested toward tips of branches; peduncle 0.2–1.6 mm. |
solitary or in small, cymose clusters at distal nodes; peduncle 0.5–3 mm. |
Euphorbia setiloba |
Euphorbia bombensis |
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Phenology | Flowering nearly year-round in response to sufficient moisture. | Flowering and fruiting spring–fall. |
Habitat | Desert scrub, blackbrush scrub, Joshua tree woodlands, grasslands, often in sandy areas. | Coastal dunes and sandy habitats. |
Elevation | 20–1600 m. (100–5200 ft.) | 0–30 m. (0–100 ft.) |
Distribution |
AZ; CA; NM; NV; TX; UT; Mexico (Baja California, Baja California Sur, Chihuahua, Durango, Sinaloa, Sonora)
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AL; FL; GA; LA; MS; NC; SC; TX; VA; Mexico; Central America; n South America (Venezuela)
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Discussion | Euphorbia bombensis is similar and closely related to E. cumulicola, E. geyeri, and E. polygonifolia. It differs notably from E. polygonifolia in its smaller, plumply ovoid seeds. L. C. Wheeler (1941) suggested that where E. bombensis and E. polygonifolia are sympatric, E. bombensis grows farther away from the shore. Euphorbia bombensis is usually distinguished from E. cumulicola by the latter's smaller, isomorphic leaves that lack any fleshiness, smaller seeds, and diffuse growth habit. Euphorbia bombensis differs from E. geyeri in its usually shorter, less conspicuous involucral gland appendages and its geographic restriction to the coastal plain. However, Wheeler pointed out that plants of E. bombensis from Texas have more or less conspicuous involucral gland appendages. Examination of specimens confirmed that E. bombensis occasionally has conspicuous involucral gland appendages, and because of this, E. bombensis and E. geyeri are difficult to distinguish in Texas. This clade of closely related, sand and dune specialists requires further study. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 12, p. 288. | FNA vol. 12, p. 261. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Chamaesyce setiloba | Chamaesyce ammannioides, C. bombensis, C. ingallsii, E. ammannioides |
Name authority | Engelmann: in War Department [U.S.], Pacif. Railr. Rep. 5(2): 364. (1857) | Jacquin: Enum. Syst. Pl., 22. (1760) |
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