Euphorbia hypericifolia |
Euphorbia ouachitana |
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graceful sandmat, graceful spurge |
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Habit | Herbs, annual, with taproot. | Herbs, annual, with taproot. |
Stems | erect to ascending, 15–50 cm, glabrous. |
erect-ascending, often basally decumbent, often branched near base, 12–28 cm, glabrous. |
Leaves | opposite; stipules connate, deltate, usually entire, sometimes laciniate-fringed at tip, 1.5–2.2 mm, glabrous; petiole 1–3 mm, glabrous; blade obliquely oblong-oblanceolate, 10–35 × 7–15 mm, base asymmetric, oblique, margins serrate or serrulate, especially toward apex, apex broadly acute, surfaces glabrous; palmately veined at base, pinnate distally. |
petiole 0–3 mm; blade broadly oblanceolate to subspatulate, or proximalmost often orbiculate, 3–20 × 3–9 mm, base attenuate, margins entire, apex rounded to emarginate, surfaces glabrous; venation pinnate, midvein prominent. |
Involucre | obconic, 0.9–1.1 × 0.4–0.9 mm, glabrous; glands 4, yellow-green to brown, stipitate, subcircular, 0.2 × 0.2 mm, occasionally nearly rudimentary; appendages absent on smaller glands or white to pink, shape highly variable, usually round to ± elliptic, 0.3–0.4 × 0.5–0.7 mm, distal margin entire. |
infundibular, 1.3–1.6 × 1–1.2 mm, glabrous; glands 4, crescent-shaped; 0.4–0.5 × 0.8–1 mm; horns divergent, 0.2–0.4 mm. |
Staminate flowers | (0–)2–20. |
15–20. |
Pistillate flowers | ovary glabrous; styles 0.4 mm, 2-fid 1/2 length. |
ovary glabrous; styles 0.8 mm, 2-fid. |
Capsules | depressed-globoid, 1.3–1.4 × 1.1–1.5 mm, glabrous; columella 1–1.1 mm. |
ovoid-globose, 2.6–2.7 × 2.5–2.7 mm, slightly lobed; cocci rounded to ± flattened, smooth, glabrous; columella 2–2.1 mm. |
Seeds | with very thin whitish mucilaginous coat over light brown testa below, ovoid-triangular, bluntly 4-angled in cross section, 0.9–1.1 × 0.5 mm, with shallow irregular depressions alternating with low, smooth ridges. |
dark brown, oblong-ovoid, 1.5–2 × 1–1.6 mm, with deep, rounded pits in 3–4 regular vertical rows; caruncle reniform-ovate, conic, 0.5–0.7 × 0.5–0.8 mm. |
Cyathia | in dense, axillary and terminal, capitate glomerules with reduced, bractlike leaves subtending cyathia; peduncle 0.5–1.8 mm. |
peduncle 0.4–0.7 mm. |
Cyathial | arrangement: terminal pleiochasial branches 3, 1–3 times 2-branched; pleiochasial bracts ovate-deltate to subrhombic-ovate, shorter and wider than distal leaves; dichasial bracts connate 1/4 length, not imbricate, broadly deltate to subreniform, base truncate to broadly obtuse, margins entire, apex obtuse to bluntly acuminate; axillary cymose branches 1–5. |
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2n | = 26. |
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Euphorbia hypericifolia |
Euphorbia ouachitana |
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Phenology | Flowering and fruiting early spring–late fall. | Flowering and fruiting spring. |
Habitat | Open, disturbed areas, nurseries. | Semiopen forests, bluffs and ledges, stream banks, glades. |
Elevation | 0–200 m. (0–700 ft.) | 100–400 m. (300–1300 ft.) |
Distribution |
AL; AR; FL; GA; LA; OK; SC; TX; Central America; South America; West Indies [Introduced in Asia, Pacific Islands]
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AR; MO; OK; TN; TX |
Discussion | Euphorbia hypericifolia is native to the New World tropics, and it is most likely adventive in the flora area (where it is most widely distributed in Florida and Texas). Reports from Arizona, California, and Maryland likely represent waifs or misidentifications. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia ouachitana is restricted to semiopen forests and woodlands in the south-central United States. It is similar to E. commutata and has been most commonly identified as that species in the past. However, it differs in its consistently brown seeds that have pits in regular, vertical rows. The two species also differ in E. commutata’s numerous, proximal, long-petiolate elliptic leaves. The proximal leaves of E. ouachitana are spatulate with an orbiculate blade and petiolelike base. Aside from the restricted distribution of E. ouachitana in Missouri and Tennessee, the ranges of E. ouachitana and E. commutata do not overlap (see M. H. Mayfield 2013 for a detailed discussion of the distribution). Euphorbia ouachitana is most common in the Ouachita Mountains from southeastern Oklahoma to Hot Springs County, Arkansas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 272. | FNA vol. 12, p. 306. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | Chamaesyce glomerifera, C. hypericifolia, E. glomerifera | |
Name authority | Linnaeus: Sp. Pl. 1: 454. (1753) | Mayfield: J. Bot. Res. Inst. Texas 7: 642, figs. 2[row 2, right], 6. (2013) |
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