Euphorbia discoidalis |
Euphorbia setiloba |
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summer spurge |
fringe spurge, shaggy spurge, Yuma sandmat |
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Habit | Herbs, perennial, with spreading rootstock. | Herbs, annual, with slender taproot. |
Stems | erect or ascending, unbranched, solitary or few, previous year's dead stems not persistent, 45–70 cm, usually densely puberulent to sericeous, rarely glabrous. |
prostrate, mat-forming, 5–50 cm, villous with glistening glandular hairs. |
Leaves | alternate; stipules to 0.1 mm; petiole (0–)1–2 mm (or absent), densely puberulent; blade usually linear, rarely ovate, 25–55 × 1.5–4 mm, base cuneate, margins entire, revolute, apex rounded, abaxial surface glabrous or puberulent to sericeous, adaxial surface glabrous; venation often obscure on smaller leaves, midvein conspicuous. |
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. |
Involucre | campanulate, 1.2–1.4 × 1.2–2 mm, sparsely to densely puberulent; glands 5, green, reniform, 0.2–0.3 × 0.5–0.6 mm; appendages white, orbiculate to oblong, (0.5–)1–1.7 × 1–1.5 mm, entire. |
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. |
Staminate flowers | 20–25. |
3–7. |
Pistillate flowers | ovary glabrous or sparsely strigose; styles 0.5–1.1 mm, 2-fid at apex to 1/2 length. |
ovary villous; styles 0.3–0.4 mm, 2-fid 1/2 length. |
Capsules | globose, 1.8–3 × 2.5–4.8 mm, glabrous or sparsely strigose; columella 2.3–2.5 mm. |
subglobose to ovoid, 1–1.2 mm diam., villous; columella 0.9–1.1 mm. |
Seeds | light gray, ovoid, 2 × 1.2–1.3 mm, smooth or with few, very shallow depressions; caruncle absent. |
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. |
Cyathia | in terminal pleiochasia; peduncle 5–15 mm, filiform, glabrous or very sparsely puberulent to sericeous. |
solitary at distal nodes, nodes often congested toward tips of branches; peduncle 0.2–1.6 mm. |
Euphorbia discoidalis |
Euphorbia setiloba |
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Phenology | Flowering and fruiting late spring–fall. | Flowering nearly year-round in response to sufficient moisture. |
Habitat | Sand hills, pine savannas, woodland borders, open fields with sandy soils. | Desert scrub, blackbrush scrub, Joshua tree woodlands, grasslands, often in sandy areas. |
Elevation | 0–150 m. (0–500 ft.) | 20–1600 m. (100–5200 ft.) |
Distribution |
AL; FL; GA; LA; MS; TX
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AZ; CA; NM; NV; TX; UT; Mexico (Baja California, Baja California Sur, Chihuahua, Durango, Sinaloa, Sonora)
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Discussion | M. J. Huft (1979) remarked that Euphorbia discoidalis is uncommon west of Alabama and referred many narrow-leaved specimens from Louisiana and Texas to E. corollata. K. R. Park (1998) included them in an expanded E. discoidalis, and that is followed here. The western populations can be distinguished from E. corollata by their shorter involucral gland appendages and revolute leaf margins. Further study of these western populations is warranted. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 12, p. 245. | FNA vol. 12, p. 288. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Alectoroctonum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Tithymalopsis discoidalis | Chamaesyce setiloba |
Name authority | Chapman: Fl. South. U.S., 401. (1860) | Engelmann: in War Department [U.S.], Pacif. Railr. Rep. 5(2): 364. (1857) |
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