Euphorbia lurida |
Euphorbia georgiana |
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woodland spurge |
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Habit | Herbs, perennial, with thick rootstock. | Herbs, annual, with taproot. |
Stems | erect or ascending, unbranched, sometimes sinuous, 5–30 cm, glabrous or sparsely to densely puberulent. |
erect, often branched near base, 10–18 cm, glabrous. |
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. |
petiole absent; blade oblanceolate, 5–12 × 3–5 mm, base attenuate, margins entire, apex rounded, surfaces glabrous; venation pinnate, midvein prominent. |
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. |
infundibular, 1–1.1 × 0.4–0.5 mm, glabrous; glands 4, crescent-shaped; 0.3–0.4 × 0.4–0.5 mm; horns divergent, 0.3–0.5 mm. |
Staminate flowers | 10–20. |
5–10. |
Pistillate flowers | ovary glabrous or puberulent; styles 0.7–1 mm, 2-fid. |
ovary glabrous; styles 0.5 mm, 2-fid. |
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-ovoid, 2.2–2.4 × 3.2–3.4 mm, 3-lobed; cocci rounded, smooth, glabrous; columella 2–2.1 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. |
gray, ovoid, 1.6–1.7 × 1.4–1.6 mm, with deep, rounded pits irregularly scattered over entire surface; caruncle reniform, subconic, 0.5–0.6 × 0.6–0.8 mm. |
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. |
arrangement: terminal pleiochasial branches 3, 1–3 times 2-branched; pleiochasial bracts rotund-obovate, wider than distal leaves; dichasial bracts distinct, not imbricate, broadly deltate to subreniform, base truncate to emarginate, margins entire, apex rounded to bluntly acuminate; axillary cymose branches 0–1. |
Cyathia | peduncle 0.3–0.9 mm. |
peduncle 0.3–0.5 mm. |
Euphorbia lurida |
Euphorbia georgiana |
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Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting spring. |
Habitat | Open pine-oak forests, dry slopes and canyons. | Granite outcrops. |
Elevation | 1300–2800 m. (4300–9200 ft.) | 100–200 m. (300–700 ft.) |
Distribution |
AZ; CA; NM; NV; UT; Mexico (Baja California)
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GA |
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 georgiana is restricted to granitic outcrops; it is known from Oglethorpe and Wilkes counties (M. H. Mayfield 2013). It is similar to E. austrotexana but has larger seeds that are much more deeply pitted and leaves that are oblanceolate instead of linear-oblanceolate to linear. It is also quite distinct from the more robust, biennial or occasionally annual E. commutata, the only other closely-related species that occurs in the area. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 305. | FNA vol. 12, p. 303. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | E. palmeri, E. palmeri var. subpubens, E. subpubens, Tithymalus luridus, T. palmeri, T. subpubens | |
Name authority | Engelmann: in J. C. Ives, Rep. Colorado R. 4: 26. (1861) | Mayfield: J. Bot. Res. Inst. Texas 7: 639, fig. 2[row 2, left]. (2013) |
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