Euphorbia setiloba |
Euphorbia chaetocalyx |
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fringe spurge, shaggy spurge, Yuma sandmat |
bristlecup sandmat |
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Habit | Herbs, annual, with slender taproot. | Herbs, perennial, with woody, thickened taproot. | ||||
Stems | prostrate, mat-forming, 5–50 cm, villous with glistening glandular hairs. |
usually erect, rarely slightly decumbent, often densely clustered from top of woody crown, 3–15 cm, glabrous. |
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Leaves | opposite; stipules distinct, filiform, rudimentary to 0.2 mm, glabrous or sparsely villous with glistening glandular hairs; petiole 0.5–1.5 mm, villous; blade oblong, ovate, or elliptic, 3–7 × 2–4 mm, base asymmetric, rounded, margins entire, apex obtuse, surfaces villous; weakly 3-veined from base, commonly only midvein conspicuous. |
opposite; stipules distinct, narrowly linear, usually entire, 0.5–1 mm, glabrous; petiole 0.5–1 mm, glabrous; blade ovate to lanceolate or oblong- or linear-lanceolate, 3–11 × 0.8–3(–5) mm, base slightly asymmetric, short-tapered, occasionally one side slightly rounded, margins entire, apex acute or short-acuminate, surfaces glabrous; only midvein conspicuous. |
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Involucre | campanulate or urceolate, 0.7–1 × 0.5–0.8 mm, villous; glands 4, red to pink, oblong to slightly reniform, 0.1–0.2 × 0.2–0.3 mm; appendages white to pink, deeply incised into 3–6 triangular to subulate, attenuate, acute segments, 0.3–0.6 × 0.6–1 mm, segments entire. |
campanulate to turbinate, 0.8–1.4 × 0.8–1 mm, glabrous; glands 4, yellow-brown to reddish, concave or convex, elliptic or oval, 0.2–0.4 × 0.4–0.6 mm; appendages absent or white, lanceolate-deltate to straplike, 0.2–1.1 × 0.2–0.9 mm, distal margin entire, crenate, or deeply cleft or divided. |
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Staminate flowers | 3–7. |
25–35. |
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Pistillate flowers | ovary villous; styles 0.3–0.4 mm, 2-fid 1/2 length. |
ovary glabrous; styles 0.3–0.4 mm, 2-fid 1/2 length. |
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Capsules | subglobose to ovoid, 1–1.2 mm diam., villous; columella 0.9–1.1 mm. |
depressed-ovoid to depressed-globose, 1.7–2.1 × 1.6–2.4 mm, glabrous; columella 1.2–1.8 mm. |
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Seeds | pink to light gray, narrowly ovoid, 4-angled in cross section, 0.8–1 × 0.5–0.6 mm, dimpled or with faint transverse ridges that do not pass through abaxial keel. |
white, ovoid-pyramidal, prominently 4-angled in cross section, 1.6–2 × 1–1.2 mm, smooth to slightly wrinkled. |
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Cyathia | solitary at distal nodes, nodes often congested toward tips of branches; peduncle 0.2–1.6 mm. |
solitary at distal nodes; peduncle 0.8–1.3 mm. |
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Euphorbia setiloba |
Euphorbia chaetocalyx |
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Phenology | Flowering nearly year-round in response to sufficient moisture. | |||||
Habitat | Desert scrub, blackbrush scrub, Joshua tree woodlands, grasslands, often in sandy areas. | |||||
Elevation | 20–1600 m. (100–5200 ft.) | |||||
Distribution |
AZ; CA; NM; NV; TX; UT; Mexico (Baja California, Baja California Sur, Chihuahua, Durango, Sinaloa, Sonora)
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AZ; NM; TX; n Mexico
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Discussion | Varieties 2 (2 in the flora). Euphorbia chaetocalyx is similar to E. fendleri but can generally be distinguished from that species by its narrow, acute leaves and ± erect stems. Some authors have used the presence or absence and shape of the involucral gland appendages to help separate E. chaetocalyx from E. fendleri, but those characters appear highly variable and of little taxonomic utility. Some individuals from western Texas (Culberson and El Paso counties) and southern New Mexico appear intermediate with E. fendleri. The specific epithet of E. chaetocalyx refers to the bristly perianthlike segments that subtend the ovary, but these structures are found intermittently in both E. chaetocalyx and E. fendleri. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 12, p. 288. | FNA vol. 12, p. 263. | ||||
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Chamaesyce setiloba | E. fendleri var. chaetocalyx, Chamaesyce chaetocalyx | ||||
Name authority | Engelmann: in War Department [U.S.], Pacif. Railr. Rep. 5(2): 364. (1857) | (Boissier) Tidestrom: Proc. Biol. Soc. Wash. 48: 40. (1935) | ||||
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