Euphorbia exstipulata |
Euphorbia ocellata |
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square-seed spurge, squareseed or Clark Mountain spurge |
Contura Creek sandmat, Contura Creek spurge, valley spurge |
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Habit | Herbs, annual, with slender taproot. | Herbs, annual, with taproot. | ||||
Stems | erect, 5–26 cm, uniformly puberulent to hispidulous or glabrous; branches arcuate. |
prostrate, 10–35 cm, glabrous or pilose. |
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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. |
opposite; stipules distinct, subulate, 0.5–1.6 mm, glabrous or pilose; petiole 0.3–2 mm, glabrous or pilose; blade ovate to deltate or falcate, 2.3–13 × 1.5–6 mm, base asymmetric, usually cordate, rarely rounded, margins occasionally reddish, entire, often revolute, apex acute to obtuse, occasionally mucronate, surfaces glabrous or pilose; midvein conspicuous, lateral veins frequently visible abaxially. |
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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. |
campanulate, 1–2.5 × 1.3–2.4 mm, glabrous or pilose; glands 4, yellow becoming deep red, elliptic or oblong to orbiculate, 0.4–0.6 × 0.5–0.7 mm; appendages absent or whitish, orbiculate, 0.1–0.2 × 0.3–0.5 mm, distal margin entire. |
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Staminate flowers | 10–12. |
30–70. |
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Pistillate flowers | ovary puberulent on keels, styles 0.8–1.1 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous or pilose; styles 0.4–0.5 mm, 2-fid at apex. |
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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. |
subglobose to broadly ovoid, 1.4–2.7 × 1.9–3.1 mm, glabrous or pilose; columella 1.4–2 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. |
whitish gray to black, ovoid to oblong, terete to bluntly subangled in cross section, 1.1–1.7 × 0.8–1.3 mm, rugose or smooth. |
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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. |
solitary at distal nodes; peduncle 0.9–2.2 mm. |
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Euphorbia exstipulata |
Euphorbia ocellata |
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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; NM; TX; UT; WY; Mexico (Chihuahua, Coahuila, Durango, Guanajuato, San Luis Potosí, Sonora, Zacatecas)
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AZ; CA; ID; NV; UT
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Discussion | 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.) |
Subspecies 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 12, p. 322. | FNA vol. 12, p. 279. | ||||
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | E. exstipulata var. lata | Chamaesyce ocellata | ||||
Name authority | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 189. (1859) | Durand & Hilgard: Pl. Heermann., 46. (1854) | ||||
Web links |