Euphorbia helioscopia |
Euphorbia serpillifolia |
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euphorbe réveille-matin, mad woman's milk, summer spurge, sun spurge, wart spurge, wartweed |
thyme leaf spurge, thyme-leafed spurge, thymeleaf sandmat |
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Habit | Herbs, annual, with taproot. | Herbs, annual, with slender taproot. | ||||
Stems | erect, unbranched or branched, 5–45 cm, usually glabrous or sparsely pilose. |
prostrate to ascending, often mat-forming, 7–35 cm, glabrous, pilose, or villous. |
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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. |
opposite; stipules distinct, divided nearly to base into 3–5 subulate to filiform segments, these sometimes 2-fid toward apex or laciniate, 0.7–2.1 mm, glabrous; petiole 0.5–1 mm, glabrous, villous, or pilose; blade ovate, oblong, elliptic, or obovate, 3–13 × 2–7 mm, base asymmetric, rounded to oblique, margins usually entire in proximal 1/2 and serrulate in distal 1/2, rarely serrulate nearly to base, apex obtuse or truncate, surfaces often with red spot in center, not papillate, glabrous, villous, or pilose; weakly 3-veined from base, usually only midvein conspicuous. |
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Involucre | cupulate, 1.5–2 × 0.7–1.1 mm, glabrous; glands 4, elliptic, 0.2–0.5 × 0.5–1 mm; horns absent. |
obconic, 0.6–1.1 × 0.6–1 mm, glabrous, villous, or pilose; glands 4, yellow to pink, usually oblong to reniform, 0.1 × 0.2–0.3 mm; appendages white to pink, oblong or flabellate, rarely absent, (0–)0.1–0.2 × (0–)0.3–0.4 mm, distal margin entire or shallowly lobed. |
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Staminate flowers | 10–15. |
5–20. |
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Pistillate flowers | ovary glabrous; styles 0.7–1 mm, 2-fid. |
ovary glabrous, villous, or pilose; styles 0.3–0.4 mm, 2-fid 1/2 length. |
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Capsules | depressed-globose, 2.5–4 × 3.2–4.2 mm, clearly 3-lobed; cocci rounded, smooth, glabrous; columella 0.9–1.1 mm. |
broadly ovoid to oblate, cocci not elongated nor terminating in empty portion, 1.4–1.9 × 1.5–2, glabrous, pilose, or villous; columella 1.2–1.6 mm. |
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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. |
pink, light brown, or grayish, ovoid to narrowly ovoid, 4-angled in cross section, 1–1.4 × 0.6–0.9 mm, smooth to dimpled or rugose, or with faint transverse ridges that do not interrupt abaxial keel. |
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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. |
solitary or in small, cymose clusters at distal nodes or on congested, axillary branches; peduncle 0.4–1.7 mm. |
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Euphorbia helioscopia |
Euphorbia serpillifolia |
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Phenology | Flowering and fruiting spring–fall. | |||||
Habitat | Roadsides, waste places. | |||||
Elevation | 0–1400 m. (0–4600 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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AZ; CA; CO; FL; GA; IA; ID; IL; MI; MN; MO; MT; ND; NE; NH; NM; NV; NY; OK; OR; PA; SD; TX; UT; WA; WI; WY; AB; BC; MB; NB; ON; QC; SK; Mexico; South America |
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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.) |
Subspecies 2 (2 in the flora). Euphorbia serpillifolia is variable, especially in regard to seed sculpturing. L. C. Wheeler (1941) documented and discussed this variation, suggesting that within the United States and Canada the taxon could be further divided into various taxa. However, Wheeler refrained from actually proposing names and commented that further study was needed. The authors concur with Wheeler and maintain a broad delimitation of the species, pending a detailed study of variation throughout its range. Otherwise indistinguishable hairy plants are treated as subsp. hirtula. In contrast to the widespread typical subspecies, subsp. hirtula ranges from northern Baja California, Mexico, to central California. In this region the two subspecies sometimes grow together. The spelling of the specific epithet follows the original publication of the name and contrasts with the often-used variant serpyllifolia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 12, p. 303. | FNA vol. 12, p. 287. | ||||
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Anisophyllum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Galarhoeus helioscopius, Tithymalus helioscopius | Chamaesyce serpillifolia | ||||
Name authority | Linnaeus: Sp. Pl. 1: 459. (1753) | Persoon: Syn. Pl. 2: 14. (1806) | ||||
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