Euphorbia polycarpa |
Euphorbia serpens |
|
---|---|---|
smallseed sandmat |
creeping spurge, Matted sandmat, Matted spurge, round-leafed spurge |
|
Habit | Herbs, annual, with slender taproot. | |
Stems | prostrate, frequently mat-forming and rooting at nodes, 15–50 cm, glabrous. |
|
Leaves | opposite; stipules connate into conspicuous, deltate scale, white to pink, membranaceous, 0.5–1(–1.2) mm, glabrous; petiole less than 1 mm, glabrous; blade ovate, oblong or orbiculate, 2–7(–9) × 2–6 mm, base asymmetric, rounded to subcordate, margins entire, apex rounded, surfaces without red blotch, glabrous; usually only midvein conspicuous. |
|
Involucre | campanulate to turbinate, 0.3–0.7(–1) × 0.4–0.6 mm, glabrous; glands 4, yellow, oblong, 0.1 × 0.2 mm; appendages white to pinkish, equal, forming narrow rim at edge of gland, 0.1–0.2 × 0.2–0.3 mm, distal margin entire or crenulate. |
|
Staminate flowers | 5–10. |
|
Pistillate flowers | ovary glabrous; styles 0.2 mm, 2-fid 1/2 to nearly entire length. |
|
Capsules | broadly ovoid, oblate, or subglobose, 1.3–1.4 × 1.3–1.7 mm, glabrous; columella (0.9–)1–1.2 mm. |
|
Seeds | white to gray or light pink, ovoid, bluntly 3–4-angled in cross section, 0.7–1.1 × 0.4–0.7 mm, smooth. |
|
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 0.5–1(–2.5) mm. |
|
Euphorbia polycarpa |
Euphorbia serpens |
|
Phenology | Flowering and fruiting year-round (in warmer areas) or summer (in temperate regions). | |
Habitat | Mostly sandy or well-drained soils, desert scrub, coastal scrub, chaparral, oak and juniper woodlands, sand dunes, riparian forests, mesquite grasslands, prairies, coniferous and deciduous hardwood forests, disturbed areas. | |
Elevation | 0–2000 m. (0–6600 ft.) | |
Distribution |
AZ; CA; NV; nw Mexico
|
AL; AR; AZ; CA; CO; FL; GA; IA; IL; IN; KS; KY; LA; MI; MO; MS; MT; ND; NE; NJ; NM; OH; OK; PA; SD; TN; TX; UT; VT; WY; ON; SK; Mexico; Central America; South America; West Indies; Bermuda [Introduced in Europe, Asia, Africa, Australia]
|
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 serpens is one of the most widespread species of the genus in the New World. While it may be indigenous to a portion of the flora area, probably in the warmer, southern part of its range, it is weedy and has likely been introduced in many parts of the flora area, such as Canada and the eastern United States. It is also widely distributed in the Old World, where it is certainly introduced. The strictly prostrate habit with stems rooting at the nodes is characteristic. Euphorbia serpens is often confused with E. albomarginata, a species distributed in the southwestern United States; in addition to the features mentioned in the key, an easy and reliable way to distinguish between them is by the size of the involucral gland appendages: those of E. albomarginata are conspicuous to the naked eye, whereas those of E. serpens are inconspicuous. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 283. | FNA vol. 12, p. 286. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Chamaesyce polycarpa | Chamaesyce serpens |
Name authority | Bentham: Bot. Voy. Sulphur, 50. (1844) | Kunth: in A. von Humboldt et al., Nov. Gen. Sp. 2(fol.): 41; 2(qto.): 52. (1817) |
Web links |
|