Euphorbia myrsinites |
Euphorbia humistrata |
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broad leaf glaucous spurge, donkey tail, myrtle or creeping or blue spurge, myrtle spurge |
spreading sandmat |
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Habit | Herbs, usually perennial, occasionally biennial, with taproot. | Herbs, annual, with taproot. |
Stems | erect or semiprostrate, unbranched or branched, 15–40 cm, succulent, glabrous. |
prostrate to ascending, usually mat-forming and rooting at nodes, 5–45 cm, sparsely to moderately villous to pilose (densely on young growth). |
Leaves | petiole 0–2 mm; blade obovate, obovate-oblong, lanceolate, orbiculate, or suborbiculate, 2–30 × 3–17 mm, fleshy, base truncate or attenuate, margins entire or finely denticulate, apex acute to obtuse, cuspidate or strongly mucronate, surfaces glabrous; venation and midvein inconspicuous. |
opposite; stipules distinct, linear-subulate, often irregularly 2- or 3-lobed, 1–1.3 mm, sparsely villous to pilose; petiole 0.5–1.5 mm, sparsely to moderately villous to pilose; blade oblong-ovate to ovate-elliptic or oblong-elliptic, 4–18 × 2.5–8 mm, base strongly asymmetric, one side angled and other rounded to auriculate, margin on longer side serrulate, on shorter side subentire, apex rounded or broadly acute, abaxial surface pale grayish green, sparsely lanulose, adaxial surface usually with irregular reddish streak along midvein, usually glabrate, rarely sparsely lanulose; palmately veined at base, pinnate distally. |
Involucre | campanulate, 2.4–2.6 × 2.3–2.5 mm, glabrous; glands 4, trapezoidal, 1–1.5 × 1.5–2.5 mm; horns divergent, thick, tips rounded, dilated, 0.5–0.9 mm. |
obconic, 0.8–1 × 0.6–0.8 mm, sparsely villous to pilose; glands 4, green to yellow-green (turning pink with age), usually ± unequal, narrowly oblong, 0.1–0.2 × 0.2–0.5 mm; appendages white to reddish tinged, lunate, ± irregular and variable in shape, 0.1–0.3 × 0.2–1.5 mm, distal margin crenulate. |
Staminate flowers | 6–12. |
2–5. |
Pistillate flowers | ovary glabrous; styles 2.5–2.8 mm, usually unbranched. |
ovary short-sericeous; styles 0.5–0.8 mm, 2-fid 1/2 length. |
Capsules | subglobose, 5–7 × 5–6 mm, unlobed; cocci rounded to subangular, smooth, glabrous; columella 4.5–5 mm. |
ovoid, well exserted from involucre at maturity, 1.3–1.5 × 1.2–1.6 mm, sparsely to moderately short-sericeous; columella 0.9–1.2 mm. |
Seeds | brownish to grayish, oblong, 2.8–4.5 × 2–3.2 mm, vermiculate-rugose; caruncle substipitate, trapezoidal or mushroom-shaped, 1.3–1.5 × 0.6–0.8 mm. |
white to light brown, oblong-ovoid, bluntly angular in cross section, 0.8–1.2 × 0.5–0.9 mm, smooth or papillate. |
Cyathial | arrangement: terminal pleiochasial branches 2–12, each 1–2 times 2-branched; pleiochasial bracts similar in shape and size to distal leaves; dichasial bracts distinct, suborbiculate or reniform, base truncate, margins entire or minutely denticulate, apex obtuse, mucronulate; axillary cymose branches 0–4. |
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Cyathia | peduncle 0.5–1 mm. |
solitary at distal nodes; peduncle 0.1–0.6(–2) mm. |
Euphorbia myrsinites |
Euphorbia humistrata |
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Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting spring–late summer. |
Habitat | Scrub oak communities, open ground near forests, shrub-steppes. | Stream and river banks, gravel bars, floodplains, pond edges, disturbed fields, railroads, roadsides. |
Elevation | 0–2400 m. (0–7900 ft.) | 0–300 m. (0–1000 ft.) |
Distribution |
CA; CO; ID; MT; NM; OR; UT; WA; WY; BC; s Europe; w Asia [Introduced in North America]
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AL; AR; FL; GA; IL; IN; KS; KY; LA; MO; MS; OH; OK; TN; TX; VA; WV
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Discussion | Euphorbia myrsinites is cultivated in much of the flora area, where it can tolerate cold winters. In some areas, it can locally escape from cultivation. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia humistrata is distributed throughout the Mississippi River valley and along other major river systems in the central and eastern United States. There are scattered reports of this species as a waif or as introduced farther north and/or east (for example, Minnesota, New York, North Carolina, Ontario, South Dakota, and Wisconsin), but the authors have not been able to verify these occurrences. Euphorbia humistrata is similar to E. maculata and is often confused with that species in herbaria. It can be distinguished from E. maculata by its tendency to root at the stem nodes, its longer styles, and its seeds that lack low transverse ridges and that are more bluntly angled. When growing side-by-side, E. humistrata has an overall less congested appearance and its cyathia are not as numerous or crowded as those of E. maculata. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 305. | FNA vol. 12, p. 272. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Tithymalus myrsinites | Chamaesyce humistrata |
Name authority | Linnaeus: Sp. Pl. 1: 461. (1753) | Engelmann: in A. Gray, Manual ed. 2, 386. (1856) |
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