Euphorbia polycarpa |
Euphorbia simulans |
|
---|---|---|
smallseed sandmat |
mimicking sandmat, similar spurge |
|
Habit | Herbs, annual or short-lived perennial, with usually slender, occasionally slightly thickened, rootstock. | |
Stems | prostrate to reclining, 5–40 cm, glabrous. |
|
Leaves | opposite; stipules distinct, subulate, 0.5–0.7 mm, glabrous; petiole 0.7–1.3 mm, glabrous; blade orbiculate, oval, to shortly oblong, 1–3.2 × 1.5–5 mm, base subsymmetric, rounded, margins entire, apex usually rounded, occasionally emarginate, surfaces glabrous; venation obscure, only midvein conspicuous. |
|
Involucre | turbinate to campanulate, 0.8–1.2 × 0.7–1 mm, glabrous; glands 4, red to purple, slightly concave, elliptic, 0.2–0.3 × 0.4–0.5 mm; appendages absent. |
|
Staminate flowers | 15–36. |
|
Pistillate flowers | ovary glabrous; styles 0.2–0.3 mm, 2-fid nearly entire length. |
|
Capsules | broadly ovoid, 1.3–1.8 × 1.5–2 mm, glabrous; columella 1.1–1.4 mm. |
|
Seeds | whitish, reddish brown beneath coat, oblong, 4-angled in cross section, 1.5–2 × 1.3–1.8 mm, with 5–7 faint transverse ridges or wrinkles. |
|
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. |
|
l | . |
|
c | . |
|
Wheeler | (1941) divided the species into seven varieties, the majority of which occur in Baja California Sur. |
|
He | reported two of these for the United States: var. hirtella and var. polycarpa. |
|
Variety | hirtella, as the name suggests, was applied to hairy plants. |
|
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. |
|
Cyathia | solitary at distal nodes; peduncle 0.3–0.7 mm. |
|
2n | = 28. |
|
Euphorbia polycarpa |
Euphorbia simulans |
|
Phenology | Flowering and fruiting year-round. | |
Habitat | Desert scrub, mountains, hills, canyons, arroyos, flats, roadsides, clay, sandy, gravelly, and rocky soils. | |
Elevation | 600–1300 m. (2000–4300 ft.) | |
Distribution |
AZ; CA; NV; nw Mexico
|
TX; Mexico (Chihuahua, Coahuila) |
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 simulans, which in the flora area is known only from Brewster, Hudspeth, and Presidio counties, is difficult to distinguish in the field from the sympatric E. theriaca var. theriaca, because they are mainly distinguished by seed morphology. The latter has smaller seeds with (two or) three (or four) prominent transverse ridges, whereas E. simulans has larger seeds that are slightly wrinkled. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 283. | FNA vol. 12, p. 289. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Chamaesyce polycarpa | E. polycarpa var. simulans, Chamaesyce simulans |
Name authority | Bentham: Bot. Voy. Sulphur, 50. (1844) | (L. C. Wheeler) Warnock & M. C. Johnston: SouthW. Naturalist 5: 170. (1960) |
Web links |