Euphorbia polycarpa |
Euphorbia jejuna |
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smallseed sandmat |
dwarf broomspurge |
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Habit | Herbs, perennial, with woody or fibrous-fleshy, napiform, branched or tuberous taproot, 3–15 mm thick. | |
Stems | ascending to erect, densely emerging from woody crown, 5–15 cm, glabrous. |
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Leaves | opposite; stipules connate into lacerate or 2-fid, lanceolate or deltate scale, 0.5–0.9 mm, glabrous; petiole 0.3–0.9 mm, glabrous; blade orbiculate-obovate, ovate, or elliptic, 3–6(–8) × 1.8–5 mm, base moderately asymmetric, rounded to truncate, margins entire, apex blunt to acute, surfaces glabrous; 2–3-veined from base but usually only midvein conspicuous. |
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Involucre | broadly campanulate, 1.2–1.5 × 0.8–1.2 mm, glabrous; glands 4, yellowish to green or purplish, oblong, 0.2–0.4 × 0.5–1 mm; appendages erect or spreading, white, 0.3–0.6 × 0.8–1.2 mm, usually deeply dissected into 4–5 acuminate lobes, rarely undivided, when divided distal margin rarely entire or crenate. |
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Staminate flowers | 12–35. |
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Pistillate flowers | ovary glabrous; styles 0.4–0.5 mm, unbranched thickened-clavate. |
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Capsules | ovoid and broadly triangular, 1.8–2.2(–2.7) × 1.5–2.1 mm, glabrous; columella 1.5–2.2 mm. |
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Seeds | whitish, oblong, 4-angled in cross section, adaxial faces concave, with long raphe between, 1.5–2(–2.3) × 0.6–0.8 mm, dimpled with faint irregular transverse wrinkles or with up to 10 low, rounded 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; peduncle 0.8–1.5 mm. |
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Euphorbia polycarpa |
Euphorbia jejuna |
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Phenology | Flowering and fruiting early spring–summer. | |
Habitat | Thin calcareous soils (caliche) on limestone hills. | |
Elevation | 500–900 m. (1600–3000 ft.) | |
Distribution |
AZ; CA; NV; nw Mexico
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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 jejuna is known in the flora area from only a few collections in Mitchell, Nolan, Terrell, and Val Verde counties. The species is very similar to E. astyla, but differs in its more deeply divided involucral gland appendages and more definitely petiolate, rounder leaves. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 283. | FNA vol. 12, p. 274. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Chamaesyce polycarpa | Chamaesyce jejuna |
Name authority | Bentham: Bot. Voy. Sulphur, 50. (1844) | M. C. Johnston & Warnock: SouthW. Naturalist 5: 97, fig. [p. 98]. (1960) |
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