Euphorbia glyptosperma |
Euphorbia serpillifolia |
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corrugate-seed spurge, rib-seed sandmat, ridge-seed spurge |
thyme leaf spurge, thyme-leafed spurge, thymeleaf sandmat |
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Habit | Herbs, annual, with taproot. | Herbs, annual, with slender taproot. | ||||
Stems | prostrate, loosely mat-forming, 5–40 cm, glabrous, sometimes slightly glaucous. |
prostrate to ascending, often mat-forming, 7–35 cm, glabrous, pilose, or villous. |
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Leaves | opposite; stipules usually distinct, linear-subulate, usually irregularly fringed or lobed, rarely laciniate, 0.4–2 mm, glabrous; petiole 0.2–2 mm, glabrous; blade narrowly oblong to oblong-obovate or oblong-ovate, 3–15 × 2–7 mm, base asymmetric, one side angled and other rounded to shallowly cordate, margins minutely sparsely serrulate, especially near apex and on longer side, apex rounded to obtuse, abaxial surface usually pale grayish green, adaxial surface sometimes reddish tinged or with reddish blotch, both surfaces glabrous; palmately veined at base, pinnate distally. |
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 | obconic, 0.6–0.9 × 0.3–0.6 mm, glabrous; glands 4, red to purple, narrowly oblong-elliptic, 0.1–0.2 × 0.1–0.5 mm; appendages white or pinkish tinged, semilunate and fringing distal margin of gland, 0.1–0.3 × 0.1–0.3 mm, distal margin usually irregularly crenulate or lobed. |
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 | 1–5. |
5–20. |
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Pistillate flowers | ovary glabrous; styles 0.1–0.3 mm, 2-fid 1/2 length. |
ovary glabrous, villous, or pilose; styles 0.3–0.4 mm, 2-fid 1/2 length. |
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Capsules | broadly ovoid, 1.3–1.9 × 1.6–2 mm, glabrous; columella 1.3–1.5 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 | with thin white coat that readily falls off, surface below tan brown, oblong-ovoid, sharply angular in cross section, 1–1.4 × 0.6–0.9 mm, with 3–4(–6) prominent transverse ridges that usually interrupt abaxial keel. |
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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Cyathia | solitary or in small, cymose clusters at distal nodes; peduncle 0.5–1.6 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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2n | = 22. |
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Euphorbia glyptosperma |
Euphorbia serpillifolia |
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Phenology | Flowering and fruiting early summer–fall. | |||||
Habitat | Stream and river banks, sand prairies, loess hill prairies, meadows, ballast, open disturbed areas, roadsides. | |||||
Elevation | 0–1800 m. (0–5900 ft.) | |||||
Distribution |
AZ; CA; CO; CT; IA; ID; IL; IN; KS; LA; MA; ME; MI; MN; MO; MT; ND; NE; NH; NM; NV; NY; OK; OR; SD; TN; TX; UT; VT; WA; WI; WY; AB; BC; MB; NB; NS; ON; PE; QC; SK; Mexico (Chihuahua, Coahuila, Tamaulipas, Zacatecas)
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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 glyptosperma is one of the most widespread species of the genus in North America, and it is often quite weedy. It is likely native to much of the central United States, but in areas like eastern Canada, it occurs in highly disturbed habitats, and it may be adventive there. Euphorbia glyptosperma is characterized by its prominently ridged seeds, laciniate stipules, complete lack of pubescence, and somewhat obscure toothing near the tips of the leaves. (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. 269. | FNA vol. 12, p. 287. | ||||
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Chamaesyce glyptosperma | Chamaesyce serpillifolia | ||||
Name authority | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 187. (1859) | Persoon: Syn. Pl. 2: 14. (1806) | ||||
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