Euphorbia setiloba |
Euphorbia angusta |
|
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fringe spurge, shaggy spurge, Yuma sandmat |
Blackfoot sandmat, narrow-leaf spurge |
|
Habit | Herbs, annual, with slender taproot. | Herbs, perennial, with moderately to strongly thickened rootstock. |
Stems | prostrate, mat-forming, 5–50 cm, villous with glistening glandular hairs. |
erect, 12–43 cm, uniformly strigose. |
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, linear-subulate or nodiform to papilliform nodiform to papilliform stipules often reddish brown, 0.1–0.7 mm, strigose; petiole 0.3–1.2 mm, strigose; blade: proximal ovate to ovate-elliptic, distal linear to elliptic-linear, 7–41 × 2–5 mm, distal leaf blades more than 6 times as long as wide, base asymmetric, cuneate to rounded, margins entire, often involute on drying, apex acute, surfaces usually short strigose, occasionally glabrous adaxially; venation pinnate, only midvein conspicuous. |
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. |
turbinate to campanulate-turbinate, 1–1.5 × 1–1.4 mm, strigose; glands 4, green to yellow-green, concave, narrowly oblong, 0.2–0.4 × 0.4–0.7 mm; appendages white, flabellate, 0.5–1.1 × 0.3–0.5 mm, distal margin shallowly and irregularly toothed. |
Staminate flowers | 3–7. |
16–26. |
Pistillate flowers | ovary villous; styles 0.3–0.4 mm, 2-fid 1/2 length. |
ovary strigose; styles 0.3–0.5 mm, 2-fid at apex to almost 1/2 length. |
Capsules | subglobose to ovoid, 1–1.2 mm diam., villous; columella 0.9–1.1 mm. |
broadly ovoid, 2–2.6 × 2.5–3 mm, strigose; columella 1.6–2.2 mm. |
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, 4-angled in cross section, 1.7–2.2 × 1.1–1.2 mm, transversely low-ridged or wrinkled. |
Cyathia | solitary at distal nodes, nodes often congested toward tips of branches; peduncle 0.2–1.6 mm. |
solitary at distal nodes; peduncle 1.1–2.4 mm. |
2n | = 28. |
|
Euphorbia setiloba |
Euphorbia angusta |
|
Phenology | Flowering nearly year-round in response to sufficient moisture. | Flowering and fruiting early spring–fall. |
Habitat | Desert scrub, blackbrush scrub, Joshua tree woodlands, grasslands, often in sandy areas. | Rocky limestone soils. |
Elevation | 20–1600 m. (100–5200 ft.) | 400–1200 m. (1300–3900 ft.) |
Distribution |
AZ; CA; NM; NV; TX; UT; Mexico (Baja California, Baja California Sur, Chihuahua, Durango, Sinaloa, Sonora)
|
TX; Mexico (Coahuila) |
Discussion | Euphorbia angusta, which in the flora area is known from the trans-Pecos region to the Edwards Plateau, is easily recognized by its erect habit, linear leaves, and relatively showy involucral gland appendages with toothed margins. The species is closely related to E. acuta and the Mexican endemic E. johnstonii Mayfield (M. H. Mayfield 1991); it is not only morphologically distinctive but is also the only species in sect. Anisophyllum with C3 photosynthesis (R. F. Sage et al. 2011; T. L. Sage et al. 2011; G. L. Webster 1975). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
|
Source | FNA vol. 12, p. 288. | FNA vol. 12, p. 260. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Chamaesyce setiloba | Chamaesyce angusta |
Name authority | Engelmann: in War Department [U.S.], Pacif. Railr. Rep. 5(2): 364. (1857) | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 189. (1859) |
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