Euphorbia chamaesula |
Euphorbia setiloba |
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mountain spurge |
fringe spurge, shaggy spurge, Yuma sandmat |
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Habit | Herbs, perennial, with thick rootstock. | Herbs, annual, with slender taproot. |
Stems | erect, branched, 40–90 cm, glabrous. |
prostrate, mat-forming, 5–50 cm, villous with glistening glandular hairs. |
Leaves | petiole 0.5–1 mm; blade elliptic to oblong, 8–20(–40) × 3–6 mm, base truncate, rounded, or attenuate, margins entire, apex obtuse or acute, sometimes slightly mucronate, surfaces glabrous; venation inconspicuous, only midvein prominent. |
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. |
Involucre | turbinate or campanulate, 1.5–2.5 × 1.1–1.9 mm, glabrous; glands 4, crescent-shaped to semicircular, 0.5–0.8 × 1–1.8 mm; horns usually convergent, 0.2–0.8 mm. |
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. |
Staminate flowers | 8–12. |
3–7. |
Pistillate flowers | ovary glabrous; styles 1–1.8 mm, 2-fid. |
ovary villous; styles 0.3–0.4 mm, 2-fid 1/2 length. |
Capsules | depressed-ovoid, 4.3–5 × 5–6 mm, 3-lobed; cocci rounded, smooth, glabrous; columella 3.5–4 mm. |
subglobose to ovoid, 1–1.2 mm diam., villous; columella 0.9–1.1 mm. |
Seeds | gray to dark brown, ovoid-oblong, truncate at both ends, 2.6–3.4 × 2–2.6 mm, shallowly pitted to almost smooth; caruncle conic, 1 × 0.8 mm. |
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. |
Cyathial | arrangement: terminal pleiochasial branches 3–5(–6), each 3–4 times 2-branched; pleiochasial bracts ovate-lanceolate to slightly subpandurate, similar in size or wider than distal leaves; dichasial bracts distinct, lanceolate to broadly ovate, base usually truncate to rounded or subcordate, sometimes attenuate, margins entire or slightly crenulate, apex usually obtuse to acute, occasionally acuminate; axillary cymose branches 2–8. |
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Cyathia | peduncle 1–3 mm. |
solitary at distal nodes, nodes often congested toward tips of branches; peduncle 0.2–1.6 mm. |
2n | = 26. |
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Euphorbia chamaesula |
Euphorbia setiloba |
|
Phenology | Flowering and fruiting spring–summer. | Flowering nearly year-round in response to sufficient moisture. |
Habitat | Clearings in ponderosa pine forests, montane roadsides, dry streambeds, creek banks, sandy and gravelly soils. | Desert scrub, blackbrush scrub, Joshua tree woodlands, grasslands, often in sandy areas. |
Elevation | 1700–2700 m. (5600–8900 ft.) | 20–1600 m. (100–5200 ft.) |
Distribution |
AZ; NM; Mexico (Chihuahua, Sonora)
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AZ; CA; NM; NV; TX; UT; Mexico (Baja California, Baja California Sur, Chihuahua, Durango, Sinaloa, Sonora)
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Discussion | Euphorbia chamaesula is easily distinguished from other perennial members of subg. Esula in western North America by its larger capsules and the vegetative shoots (without cyathia) that arise from the distal nodes of the stem proximal to the pleiochasia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 12, p. 300. | FNA vol. 12, p. 288. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Tithymalus chamaesula | Chamaesyce setiloba |
Name authority | Boissier: Cent. Euphorb., 38. (1860) | Engelmann: in War Department [U.S.], Pacif. Railr. Rep. 5(2): 364. (1857) |
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