Euphorbia discoidalis |
Euphorbia deltoidea |
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summer spurge |
wedge sandmat |
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Habit | Herbs, perennial, with spreading rootstock. | Herbs, perennial, delicate, with woody, thickened taproot, 15 mm diam.. | ||||||||||||||||
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, ascending, or erect, often numerous and wiry, less than 0.1 mm diam., 5–20 cm, glabrous, puberulent, canescent, villous, or hirsute, shorter hairs often uncinate and longer hairs straight or irregularly twisted. |
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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, triangular, sometimes lacerate or ciliate, 0.2–0.3 mm, glabrous or hairy; petiole 0.3–1 mm, glabrous or hairy; blade narrowly to broadly deltate, cordate, or reniform, 2–5(–7) × 1–4.5(–5) mm, base asymmetric, cordate to rounded, margins entire, ± revolute, apex obtuse or rounded, surfaces glabrous or hairy; only midvein conspicuous. |
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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. |
turbinate to campanulate, 0.8–1 × 1.1–1.3 mm, glabrous or hairy; glands 4, green to yellow-green, oblong to subcircular, 0.2–0.4 × 0.4–0.6 mm; appendages absent or white, forming narrow rim at edge of gland, rarely slightly wider than gland, (0–)0.1(–0.3) × 0.4–0.6 mm, distal margin entire. |
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Staminate flowers | 20–25. |
8–14. |
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Pistillate flowers | ovary glabrous or sparsely strigose; styles 0.5–1.1 mm, 2-fid at apex to 1/2 length. |
ovary glabrous or hairy, subtended by triangular pad of tissue; styles spreading, 0.3–0.4 mm, 2-fid 1/2 to nearly entire length. |
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Capsules | globose, 1.8–3 × 2.5–4.8 mm, glabrous or sparsely strigose; columella 2.3–2.5 mm. |
broadly deltoid, 1.2–1.5 × 2–2.2 mm, glabrous or hairy; columella 0.9–1.3 mm. |
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Seeds | light gray, ovoid, 2 × 1.2–1.3 mm, smooth or with few, very shallow depressions; caruncle absent. |
reddish brown, ovoid, 4-angled in cross section, 0.8–1.2 × 0.5–0.6 mm, obscurely wrinkled. |
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Cyathia | in terminal pleiochasia; peduncle 5–15 mm, filiform, glabrous or very sparsely puberulent to sericeous. |
solitary at distal nodes; peduncle 0.7–1.5 mm. |
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Euphorbia discoidalis |
Euphorbia deltoidea |
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Phenology | Flowering and fruiting late spring–fall. | |||||||||||||||||
Habitat | Sand hills, pine savannas, woodland borders, open fields with sandy soils. | |||||||||||||||||
Elevation | 0–150 m. (0–500 ft.) | |||||||||||||||||
Distribution |
AL; FL; GA; LA; MS; TX
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FL |
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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.) |
Subspecies 4 (4 in the flora). Euphorbia deltoidea comprises four narrowly endemic subspecies, all of which are endangered due to habitat loss and fragmentation. The subspecies occur in pine rockland habitat that is free of shrubby undergrowth. Periodic fires are required to keep the rockland habitat open. Subspecies serpyllum is restricted to Big Pine Key, Monroe County, whereas the other subspecies are found only in Miami-Dade County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 12, p. 245. | FNA vol. 12, p. 265. | ||||||||||||||||
Parent taxa | Euphorbiaceae > Euphorbia > sect. Alectoroctonum | Euphorbiaceae > Euphorbia > sect. Anisophyllum | ||||||||||||||||
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Synonyms | Tithymalopsis discoidalis | Chamaesyce deltoidea | ||||||||||||||||
Name authority | Chapman: Fl. South. U.S., 401. (1860) | Engelmann ex Chapman: Fl. South. U.S. ed. 2, 647. (1883) | ||||||||||||||||
Web links |