Euphorbia exstipulata |
Euphorbia corollata |
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square-seed spurge, squareseed or Clark Mountain spurge |
eastern flowering spurge, flowering spurge, floweringspurge euphorbia |
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Habit | Herbs, annual, with slender taproot. | Herbs, perennial, with deep, spreading rootstock. |
Stems | erect, 5–26 cm, uniformly puberulent to hispidulous or glabrous; branches arcuate. |
erect or ascending, usually unbranched, occasionally few branched, solitary or few, previous year's dead stems not persistent, 20–100 cm, glabrous or slightly pilose to villous. |
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. |
alternate, ascending; stipules 0.1–0.2 mm; petiole minute or absent; blade oblanceolate, obovate, or elliptic, 25–55 × 5–12 mm, base cuneate to rounded, margins entire, occasionally slightly revolute, apex rounded to subacute, abaxial surface glabrous or pilose to villous, adaxial surface usually glabrous, rarely villous; venation occasionally obscure on small leaves, midvein conspicuous. |
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, 1.2–1.5 × 1.2–1.5(–2) mm, glabrous or moderately puberulent (especially near glands); glands 5, green, reniform, 0.5 × 0.8–1 mm; appendages white, flabellate, 2.5–3.5(–4.5) × 2.5–3.2 mm, entire. |
Staminate flowers | 10–12. |
20–25. |
Pistillate flowers | ovary puberulent on keels, styles 0.8–1.1 mm, 2-fid 1/2 to nearly entire length. |
ovary glabrous; styles 0.8–1.4 mm, 2-fid at apex to 1/2 length. |
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. |
globose, 2.3–3 × 3.5–4.2 mm, glabrous; columella 2–2.5 mm. |
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. |
white or light gray, ovoid, 2.5–2.8 × 2.2 mm, with shallow and coarse depressions; caruncle absent. |
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. |
in terminal pleiochasia, dichasial bracts occasionally whorled or rarely alternate; peduncle (1.5–)5–11(–13) mm (proximal to 70 mm), glabrous. |
Euphorbia exstipulata |
Euphorbia corollata |
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Phenology | Flowering and fruiting summer–fall. | Flowering and fruiting early summer–fall. |
Habitat | Desert scrub, grasslands, mesquite savannas, oak and oak-juniper woodlands. | Prairies, open fields, upland woods, glades, barrens, borders of swamps, roadsides, disturbed sites. |
Elevation | 800–2000 m. (2600–6600 ft.) | 0–1300 m. (0–4300 ft.) |
Distribution |
AZ; CA; NM; TX; UT; WY; Mexico (Chihuahua, Coahuila, Durango, Guanajuato, San Luis Potosí, Sonora, Zacatecas)
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AL; AR; CT; DE; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NE; NH; NJ; NY; OH; OK; PA; RI; SC; SD; TN; TX; VA; VT; WI; WV; ON
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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.) |
Euphorbia corollata is morphologically variable and widely distributed across a large part of eastern North America. The species appears to be expanding its range, as adventive populations have been reported from disturbed habitats at the northern edge of its range in Maine, Massachusetts, Michigan, Minnesota, New Hampshire, South Dakota, and Vermont. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 322. | FNA vol. 12, p. 244. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Alectoroctonum |
Sibling taxa | ||
Synonyms | E. exstipulata var. lata | E. corollata var. molle, E. corollata var. viridiflora, E. marilandica, E. olivacea, Tithymalopsis corollata, T. olivacea |
Name authority | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 189. (1859) | Linnaeus: Sp. Pl. 1: 459. (1753) |
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