Euphorbia pediculifera |
Euphorbia exstipulata |
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Carrizo Mountain sandmat |
square-seed spurge, squareseed or Clark Mountain spurge |
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Habit | Herbs, annual, with slender taproot. | |
Stems | erect, 5–26 cm, uniformly puberulent to hispidulous or glabrous; branches arcuate. |
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Leaves | opposite; petiole 1–3 mm, often indistinct, glabrous or puberulent; blade linear to narrowly elliptic or ovate, 14–42 × 3–28 mm, base attenuate, margins coarsely serrate, occasionally revolute, apex acute to obtuse, abaxial surface sparsely hispidulous to strigillose, adaxial surface glabrous; midvein conspicuous. |
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Involucre | turbinate to campanulate, 1.1–1.5 × 1–1.3 mm, glabrous, pilose or puberulent; involucral lobes divided into several linear lobes; glands 4(–5), yellow to pink, sessile and broadly attached, 0.2 × 0.3–0.4 mm, opening oblong to nearly circular, glabrous; appendages usually petaloid, white to pink, ovate to trapezoidal, occasionally absent, not incurved and covering glands, 0.2–0.4 × 0.3–0.8 mm, entire, undulate, or conspicuously divided into triangular segments, glabrous. |
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Staminate flowers | 10–12. |
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Pistillate flowers | ovary puberulent on keels, styles 0.8–1.1 mm, 2-fid 1/2 to nearly entire length. |
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Capsules | broadly depressed-oblong to ovoid, 2.7–3.3 × 3.1–3.9 mm, puberulent (with appressed hairs usually concentrated on keels); columella 1.9–2.5 mm. |
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Seeds | white to gray or light brown, ovoid, bluntly 4-angled in cross section, 1.9–2.5 × 1.4–1.7 mm, tuberculate, often with 2 transverse ridges; caruncle 0.1 × 0.2 mm. |
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Euphorbia | pediculifera can be variable in terms of leaf shape and the extent of pubescence, but the species is readily identified by the short, appressed hairs on the leaves and the distinctive seed that is encircled by a series of round, transverse ridges. |
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Cyathial | arrangement: terminal cymose or dichasial branches usually 1–2, occasionally reduced to monochasia, 1–2-branched; pleiochasial bracts 2–4, often whorled, wholly green or paler green at base, similar in shape and size to distal leaves or slightly narrower; dichasial bracts similar in shape to distal leaves but smaller or highly reduced. |
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Cyathia | peduncle 1–1.9 mm. |
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Euphorbia pediculifera |
Euphorbia exstipulata |
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Phenology | Flowering and fruiting summer–fall. | |
Habitat | Desert scrub, grasslands, mesquite savannas, oak and oak-juniper woodlands. | |
Elevation | 800–2000 m. (2600–6600 ft.) | |
Distribution |
AZ; CA; nw Mexico
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AZ; CA; NM; TX; UT; WY; Mexico (Chihuahua, Coahuila, Durango, Guanajuato, San Luis Potosí, Sonora, Zacatecas)
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Discussion | Varieties 2 (1 in the flora). Euphorbia pediculifera var. linearifolia S. Watson is found only near Guaymas in southwestern Sonora, Mexico. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia exstipulata is native from Texas to California and northern Mexico. The species was found once in the late nineteenth century in Wyoming but has not been re-collected there. Broad-leaved plants have been segregated as var. lata, but the variation in leaf shape is continuous and no varieties are formally recognized here. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 281. | FNA vol. 12, p. 322. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Poinsettia |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Chamaesyce pediculifera | E. exstipulata var. lata |
Name authority | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 186. (1859) | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 189. (1859) |
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