Euphorbia lurida |
Euphorbia serpillifolia |
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woodland spurge |
thyme leaf spurge, thyme-leafed spurge, thymeleaf sandmat |
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Habit | Herbs, perennial, with thick rootstock. | Herbs, annual, with slender taproot. | ||||
Stems | erect or ascending, unbranched, sometimes sinuous, 5–30 cm, glabrous or sparsely to densely puberulent. |
prostrate to ascending, often mat-forming, 7–35 cm, glabrous, pilose, or villous. |
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Leaves | petiole 0–1 mm; blade oblanceolate to obovate, 8–20 mm × 3–7 mm, base truncate or cuneate, margins entire, apex obtuse to rounded, minutely mucronate, surfaces puberulent or glabrous; venation inconspicuous, only 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, 2–2.2 × 1.3–1.8 mm, glabrous; glands 4, oblong to broadly ovate, usually truncate, 0.5–0.8 × 1–1.6 mm, margins irregularly crenate to strongly dentate; horns absent or usually divergent or straight, 0.1–0.3 mm, usually slightly longer than, occasionally equaling, teeth on gland margin. |
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 | 10–20. |
5–20. |
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Pistillate flowers | ovary glabrous or puberulent; 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 | ovoid, 3.5–4 × 4–4.5 mm, 3-lobed; cocci rounded, smooth to slightly rugose, glabrous; columella 3.2–3.5 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 | gray to dark gray, truncate-oblong to truncate-ovoid, 2.8–3 × 1.7–2 mm, irregularly pitted; caruncle conic, 0.6 × 0.7 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 1–4 times 2-branched; pleiochasial bracts ovate to broadly ovate or oblanceolate, wider than distal leaves; dichasial bracts distinct, rounded, oblanceolate, or subreniform, base cuneate or obtuse, margins entire, apex obtuse, slightly mucronate; axillary cymose branches 0–4. |
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Cyathia | peduncle 0.3–0.9 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 lurida |
Euphorbia serpillifolia |
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Phenology | Flowering and fruiting spring–summer. | |||||
Habitat | Open pine-oak forests, dry slopes and canyons. | |||||
Elevation | 1300–2800 m. (4300–9200 ft.) | |||||
Distribution |
AZ; CA; NM; NV; UT; Mexico (Baja California)
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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 lurida has been treated as a complex of several taxa in the past, but only a single, broadly-defined species is recognized here. This species is variable in both the pubescence and shape of the bracts subtending the cyathia and also in the degree of crenation of the gland margin. In the northern part of its range, E. lurida appears to intergrade with E. brachycera, and it can be difficult to distinguish these two species in northern Arizona and New Mexico. A report of the species from Sonora, Mexico, based on a single immature collection (V. W. Steinmann and R. S. Felger 1997) has not been verified. (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. 305. | FNA vol. 12, p. 287. | ||||
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Anisophyllum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | E. palmeri, E. palmeri var. subpubens, E. subpubens, Tithymalus luridus, T. palmeri, T. subpubens | Chamaesyce serpillifolia | ||||
Name authority | Engelmann: in J. C. Ives, Rep. Colorado R. 4: 26. (1861) | Persoon: Syn. Pl. 2: 14. (1806) | ||||
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