Euphorbia polycarpa |
Euphorbia cumulicola |
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smallseed sandmat |
coastal dune sandmat |
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Habit | Herbs, usually annual, rarely perennial, with taproot. | |
Stems | prostrate, 10–20 cm, glabrous. |
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Leaves | opposite; stipules distinct, linear-subulate, usually divided into 3–7 linear segments, 0.5–1 mm, glabrous; petiole 0.5–1 mm, glabrous; blade narrowly elliptic to lanceolate, 4–8 × 1–2 mm uniform in size, base asymmetric, obtuse to rounded, margins entire, apex obtuse to acute, surfaces green to reddish flushed, glabrous; only midvein conspicuous. |
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Involucre | campanulate, 0.9–1.1 × 1–1.3 mm, glabrous; glands 4, green to red, slightly stipitate, subcircular, 0.1 × 0.1 mm; appendages white or pink, fringing edge of gland, short-flabellate, often rudimentary, 0.1–0.2 × 0.1 mm, distal margin crenate or entire. |
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Staminate flowers | 5–8. |
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Pistillate flowers | ovary glabrous; styles 0.2–0.3 mm, 2-fid at apex to nearly 1/2 length. |
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Capsules | ovoid or subglobose, 1.8–2 × 2–2.3 mm, glabrous; columella 1.2–1.5 mm. |
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Seeds | white to gray-brown, ovoid, terete to bluntly subangled in cross section, 1–1.3 × 1 mm, smooth or minutely pitted, with smooth brown line from top to bottom on adaxial side. |
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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; peduncle 1 mm. |
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Euphorbia polycarpa |
Euphorbia cumulicola |
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Phenology | Flowering and fruiting year-round. | |
Habitat | Sandy oak hammocks, open sandy areas behind mangroves, disturbed sandy sites. | |
Elevation | 0–10 m. (0–0 ft.) | |
Distribution |
AZ; CA; NV; nw Mexico
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FL |
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 cumulicola could be confused with E. bombensis, both of which are widespread in Florida, but there the latter occurs on beaches close to the ocean, whereas E. cumulicola is not a beach-inhabiting species but occurs in more protected sandy habitats such as hammocks or stabilized dunes behind mangroves. Also, E. bombensis has fleshier leaves and larger seeds, and is more compact in habit than E. cumulicola, which is a more sprawling and densely branched plant with leaves that are usually purplish tinged along the margins. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 283. | FNA vol. 12, p. 265. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Chamaesyce polycarpa | Chamaesyce cumulicola |
Name authority | Bentham: Bot. Voy. Sulphur, 50. (1844) | (Small) Oudejans: Phytologia 67: 45. (1989) |
Web links |