Euphorbia lurida |
Euphorbia mercurialina |
|
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woodland spurge |
Mercury spurge |
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Habit | Herbs, perennial, with thick rootstock. | Herbs, perennial, with thickened, spreading rootstock. |
Stems | erect or ascending, unbranched, sometimes sinuous, 5–30 cm, glabrous or sparsely to densely puberulent. |
erect, unbranched or branched, solitary or few, previous year's dead stems not persistent, 20–33 cm, glabrous or villous to lanate. |
Leaves | petiole 0–1 mm; blade oblanceolate to obovate, 8–20 mm × 3–7 mm, base truncate or cuneate, margins entire, apex obtuse to rounded, minutely mucronate, surfaces puberulent or glabrous; venation inconspicuous, only midvein prominent. |
alternate; stipules 0.1–0.2 mm; petiole (1–)2.5–5(–6) mm, ciliate to lanate; blade elliptic to ovate-deltate, proximal greatly reduced, scalelike, 34–55 × 20–26 mm, base rounded or cuneate, margins entire, densely ciliate, apex rounded to acute, abaxial surface sparsely pilose to villous (to lanate on midrib), adaxial surface glabrous; venation obscure, only midvein conspicuous. |
Involucre | cupulate, 2–2.2 × 1.3–1.8 mm, glabrous; glands 4, oblong to broadly ovate, usually truncate, 0.5–0.8 × 1–1.6 mm, margins irregularly crenate to strongly dentate; horns absent or usually divergent or straight, 0.1–0.3 mm, usually slightly longer than, occasionally equaling, teeth on gland margin. |
campanulate or hemispheric, 1.5–2.5 × 2–3 mm, glabrous; glands 5, green, elliptic-reniform, 0.5 × 2 mm; appendages white, narrowly transversely-oblong to lunate, 0.6 × 2.5 mm, slightly erose. |
Staminate flowers | 10–20. |
10–15. |
Pistillate flowers | ovary glabrous or puberulent; styles 0.7–1 mm, 2-fid. |
ovary glabrous; styles 0.7–1.5 mm, 2-fid at apex. |
Capsules | ovoid, 3.5–4 × 4–4.5 mm, 3-lobed; cocci rounded, smooth to slightly rugose, glabrous; columella 3.2–3.5 mm. |
depressed-globose, 2.3–3.3 × 4.4–5 mm, glabrous; columella 2.7–3 mm. |
Seeds | gray to dark gray, truncate-oblong to truncate-ovoid, 2.8–3 × 1.7–2 mm, irregularly pitted; caruncle conic, 0.6 × 0.7 mm. |
tan to dark brown, ovoid, 2.2 × 1.6 mm, with shallow and coarse depressions; caruncle absent. |
Cyathial | arrangement: terminal pleiochasial branches 3–5, each 1–4 times 2-branched; pleiochasial bracts ovate to broadly ovate or oblanceolate, wider than distal leaves; dichasial bracts distinct, rounded, oblanceolate, or subreniform, base cuneate or obtuse, margins entire, apex obtuse, slightly mucronate; axillary cymose branches 0–4. |
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Cyathia | peduncle 0.3–0.9 mm. |
usually in terminal pleiochasia, rarely dichasia; peduncle 1.3–2.7 mm (to 40–70 mm for central cyathium), filiform, glabrous. |
Euphorbia lurida |
Euphorbia mercurialina |
|
Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting spring. |
Habitat | Open pine-oak forests, dry slopes and canyons. | Dry to mesic wooded slopes and ravines. |
Elevation | 1300–2800 m. (4300–9200 ft.) | 100–600 m. (300–2000 ft.) |
Distribution |
AZ; CA; NM; NV; UT; Mexico (Baja California)
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AL; GA; KY; NC; TN
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Discussion | Euphorbia lurida has been treated as a complex of several taxa in the past, but only a single, broadly-defined species is recognized here. This species is variable in both the pubescence and shape of the bracts subtending the cyathia and also in the degree of crenation of the gland margin. In the northern part of its range, E. lurida appears to intergrade with E. brachycera, and it can be difficult to distinguish these two species in northern Arizona and New Mexico. A report of the species from Sonora, Mexico, based on a single immature collection (V. W. Steinmann and R. S. Felger 1997) has not been verified. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia mercurialina is restricted primarily to the Cumberland Plateau and southern Appalachians, with disjunct occurrences in south-central North Carolina in the lower Piedmont. The North Carolina plants are markedly hairier than plants elsewhere, with villous or lanate stems, petioles, and abaxial leaf midribs. Euphorbia mercurialina has been reported from Florida and Virginia in the past. The Virginia plants were apparently planted (A. S. Weakley 2010), and the Florida reports are most certainly in error. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 305. | FNA vol. 12, p. 249. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Alectoroctonum |
Sibling taxa | ||
Synonyms | E. palmeri, E. palmeri var. subpubens, E. subpubens, Tithymalus luridus, T. palmeri, T. subpubens | Tithymalopsis mercurialina |
Name authority | Engelmann: in J. C. Ives, Rep. Colorado R. 4: 26. (1861) | Michaux: Fl. Bor.-Amer. 2: 212. (1803) |
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