Euphorbia lurida |
Euphorbia exigua |
|
---|---|---|
woodland spurge |
dwarf spurge, small spurge |
|
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, unbranched or branched, 3–30 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 0–0.5 mm; blade linear, linear-oblong, or linear-spatulate, 2–30 × 1–5 mm, base cuneate or truncate, margins entire, apex acute, obtuse, or emarginate, surfaces glabrous; venation inconspicuous, only 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. |
cupulate, 0.3–0.5 × 0.6–0.8 mm, glabrous; glands 4, elliptic to crescent-shaped, 0.2–0.4 × 0.3–0.6 mm; horns divergent, 0.2–0.5 mm. |
Staminate flowers | 10–20. |
5–8. |
Pistillate flowers | ovary glabrous or puberulent; styles 0.7–1 mm, 2-fid. |
ovary glabrous; styles 0.5–0.7 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. |
subglobose, 1–1.8 × 1.3–2 mm, slightly lobed; cocci rounded, smooth, puncticulate toward abaxial line, glabrous; columella 1.1–1.4 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. |
blackish to grayish, 4-angled-ovoid, 1–1.5 × 0.5–0.7 mm, white, tuberculate; caruncle conic or subconic, 0.1–0.3 × 0.1–0.3 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 3–5, each 1–3 times 2-branched; pleiochasial bracts similar in shape and size to or sometimes slightly longer and wider than distal leaves; dichasial bracts distinct, linear, or linear-lanceolate, or lanceolate-ovate, base rounded to subcordate, margins entire, apex acute; axillary cymose branches 0–5. |
Cyathia | peduncle 0.3–0.9 mm. |
peduncle 0–2 mm. |
Euphorbia lurida |
Euphorbia exigua |
|
Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting summer–fall. |
Habitat | Open pine-oak forests, dry slopes and canyons. | Edges of gardens, roadsides, waste places. |
Elevation | 1300–2800 m. (4300–9200 ft.) | 0–1500 m. (0–4900 ft.) |
Distribution |
AZ; CA; NM; NV; UT; Mexico (Baja California)
|
CA; NY; WV; BC; NS; ON; Europe; w Asia; n Africa; Atlantic Islands (Macaronesia) [Introduced in North America] |
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 exigua can be easily distinguished from other annual species of the genus in the flora area by its tuberculate seeds. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 305. | FNA vol. 12, p. 302. |
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 | Tithymalus exiguus |
Name authority | Engelmann: in J. C. Ives, Rep. Colorado R. 4: 26. (1861) | Linnaeus: Sp. Pl. 1: 456. (1753) |
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