Euphorbia polycarpa |
Euphorbia velleriflora |
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smallseed sandmat |
Caliche sandmat |
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Habit | Herbs, perennial, with strongly thickened and lignified rootstock. | |
Stems | prostrate, usually mat-forming, terete to slightly flattened and winged, to 30 cm, villous to pilose. |
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Leaves | opposite; stipules distinct or connate at base, 2-fid to laciniate into 2–5 linear to subulate divisions, 0.5–1(–2) mm, glabrous or villous; petiole 0.5–2 mm, villous; blade usually ovate to oblong, rarely suborbiculate, 5–13 × 4–8 mm, base asymmetric, hemicordate, margins serrulate, apex obtuse, surfaces villous; 3-veined from base, usually only midvein conspicuous. |
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Involucre | turbinate, 0.9–1.4 × 0.7–1.1 mm, villous; glands 4, pink, oblong to reniform, 0.1–0.2 × 0.3–0.4 mm; appendages white to pink, flabellate, ovate, or oblong, 0.3–0.5 × 0.4–0.7 mm, distal margin entire, crenulate, or erose, often puberulent-ciliate. |
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Staminate flowers | 8–12. |
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Pistillate flowers | ovary villous; styles 0.2–0.4(–0.5) mm, 2-fid 1/2 length. |
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Capsules | broadly ovoid, 1.5–1.9 × 1.3–1.7 mm, villous (uniformly so, but most pronounced toward base and along keels); columella 1.2–1.4 mm. |
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Seeds | white to gray or pink, narrowly pyramidal-ovoid, 4-angled in cross section, 1.1–1.3 × 0.4–0.6 mm, rugulose with shallow depressions separated by inconspicuous transverse ridges. |
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Euphorbia | polycarpa is a highly variable species distributed throughout the Baja California peninsula, eastern Sonora, and the arid southwestern United States from southwestern Arizona to southern Nevada and central California. |
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l | . |
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c | . |
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Wheeler | (1941) divided the species into seven varieties, the majority of which occur in Baja California Sur. |
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He | reported two of these for the United States: var. hirtella and var. polycarpa. |
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Variety | hirtella, as the name suggests, was applied to hairy plants. |
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However | , it is here treated as a synonym of var. polycarpa, because variation in pubescence shows no geographic segregation and ranges along a continuum from glabrous or sparsely to densely hairy, and because glabrous and hairy branches can occur on the same individual. |
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Cyathia | solitary at distal nodes or at nodes of leafy, congested, axillary branches; peduncle 1–1.5(–2.5) mm. |
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Euphorbia polycarpa |
Euphorbia velleriflora |
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Phenology | Flowering and fruiting summer. | |
Habitat | Disturbed habitats, particularly roadsides, grasslands, live oak-thorn scrub. | |
Elevation | 50–80 m. (200–300 ft.) | |
Distribution |
AZ; CA; NV; nw Mexico
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TX; Mexico; Central America (Guatemala) [Introduced in North America] |
Discussion | Varieties 5 (1 in the flora). Some of the varieties occurring in Mexico are highly divergent and appear to be sufficiently distinct to merit recognition as species. However, within the flora area, Euphorbia polycarpa is relatively uniform, and the only noteworthy variation involves the size of the involucral gland appendages. In the portion of the California Floristic Province occupied by E. polycarpa (Los Angeles, Orange, western Riverside, western San Diego, and Ventura counties) the appendages are conspicuously larger than those of plants throughout the remainder of its range in the southwestern United States (0.4–1.2 versus 0.1–0.3 mm). Large-appendaged plants are also common in Baja California and correspond well with the type collection. The taxonomic significance of this variation is not clear at this time, and the small-appendaged plants may merit segregation as an infraspecific taxon. However, no formal changes are proposed, awaiting a comprehensive review of the species throughout its range. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia velleriflora is native and widespread from northern Mexico to Guatemala. The species is apparently a recent introduction in southern Texas (W. R. Carr and M. H. Mayfield 1993), as the first records are from the 1990s. It is also expected in southern Arizona due to the presence of collections made a few kilometers south of the border in the Mexican state of Sonora. Euphorbia velleriflora is very similar to E. stictospora, and the two are sometimes confused. The two can be readily distinguished on the basis of their styles: unbranched in E. stictospora and 2-fid in E. velleriflora. Also, the involucral gland appendages of E. velleriflora are ciliate with short hairs, whereas those of E. stictospora are glabrous. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 283. | FNA vol. 12, p. 292. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Chamaesyce polycarpa | Anisophyllum velleriflorum, Chamaesyce velleriflora |
Name authority | Bentham: Bot. Voy. Sulphur, 50. (1844) | (Klotzsch & Garcke) Boissier: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 15(2): 40. (1862) |
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