Euphorbia helioscopia |
Euphorbia discoidalis |
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euphorbe réveille-matin, mad woman's milk, summer spurge, sun spurge, wart spurge, wartweed |
summer spurge |
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Habit | Herbs, annual, with taproot. | Herbs, perennial, with spreading rootstock. |
Stems | erect, unbranched or branched, 5–45 cm, usually glabrous or sparsely pilose. |
erect or ascending, unbranched, solitary or few, previous year's dead stems not persistent, 45–70 cm, usually densely puberulent to sericeous, rarely glabrous. |
Leaves | petiole absent or to 0.5 mm; blade obovate-spatulate, 4–40 × 2–25 mm, base cuneate, attenuate, or auriculate, margins serrulate, apex rounded, surfaces glabrous; venation pinnate, midvein prominent. |
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. |
Involucre | cupulate, 1.5–2 × 0.7–1.1 mm, glabrous; glands 4, elliptic, 0.2–0.5 × 0.5–1 mm; horns absent. |
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. |
Staminate flowers | 10–15. |
20–25. |
Pistillate flowers | ovary glabrous; styles 0.7–1 mm, 2-fid. |
ovary glabrous or sparsely strigose; styles 0.5–1.1 mm, 2-fid at apex to 1/2 length. |
Capsules | depressed-globose, 2.5–4 × 3.2–4.2 mm, clearly 3-lobed; cocci rounded, smooth, glabrous; columella 0.9–1.1 mm. |
globose, 1.8–3 × 2.5–4.8 mm, glabrous or sparsely strigose; columella 2.3–2.5 mm. |
Seeds | dark brown to blackish, subovoid, 1.6–2.2 × 1.5–1.9 mm, reticulate; caruncle elliptic, 0.9–1.1 × 0.4–0.5 mm. |
light gray, ovoid, 2 × 1.2–1.3 mm, smooth or with few, very shallow depressions; caruncle absent. |
Cyathial | arrangement: terminal pleiochasial branches (3–)5, each 1–2 times 2-branched; pleiochasial bracts obovate, wider than distal leaves; dichasial bracts distinct, obovate or rhombic, ± oblique, base rounded, truncate, or attenuate, margins serrulate, apex rounded; axillary cymose branches 0. |
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Cyathia | peduncle 0.2–1 mm. |
in terminal pleiochasia; peduncle 5–15 mm, filiform, glabrous or very sparsely puberulent to sericeous. |
Euphorbia helioscopia |
Euphorbia discoidalis |
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Phenology | Flowering and fruiting spring–fall. | Flowering and fruiting late spring–fall. |
Habitat | Roadsides, waste places. | Sand hills, pine savannas, woodland borders, open fields with sandy soils. |
Elevation | 0–1400 m. (0–4600 ft.) | 0–150 m. (0–500 ft.) |
Distribution |
CA; CT; DC; DE; GA; ID; IL; LA; MA; MD; ME; MI; MT; NC; NH; NJ; NY; OH; OR; PA; SC; TN; TX; VA; VT; WA; WI; WY; AB; BC; NB; NF; NS; ON; PE; QC; SK; Europe; Asia; n Africa [Introduced in North America; introduced also in South America (Argentina, Chile)]
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AL; FL; GA; LA; MS; TX
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Discussion | Euphorbia helioscopia was collected once in Minnesota in the late 1800s but apparently did not become established there. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 12, p. 303. | FNA vol. 12, p. 245. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Alectoroctonum |
Sibling taxa | ||
Synonyms | Galarhoeus helioscopius, Tithymalus helioscopius | Tithymalopsis discoidalis |
Name authority | Linnaeus: Sp. Pl. 1: 459. (1753) | Chapman: Fl. South. U.S., 401. (1860) |
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