Euphorbia brachycera |
Euphorbia longicruris |
|
---|---|---|
horned spurge, shorthorn spurge |
wedge-leaf spurge |
|
Habit | Herbs, perennial, with thick rootstock. | Herbs, annual, with taproot. |
Stems | erect or ascending, branched, 10–60 cm, usually glabrous, sometimes puberulent. |
erect, usually unbranched, occasionally branched later in season, 5–25 cm, glabrous. |
Leaves | petiole 0–0.5 mm; blade oblong-elliptic, lanceolate, or oblanceolate to broadly ovate, 5–25 × 2–7 mm, base truncate, rounded, acute, or attenuate, margins entire, apex acute or obtuse, sometimes mucronate, surfaces usually glabrous, sometimes puberulent; venation inconspicuous, only midvein prominent. |
petiole 0–0.5 mm; blade cuneate-spatulate to obovate, 5–15 × 2–6 mm, base broadly attenuate, margins entire, apex rounded to obtuse, mucronate, surfaces glabrous; venation pinnate, midvein prominent. |
Involucre | turbinate, campanulate or cupulate, 1.5–2.6 × 1.4–1.7 mm, usually glabrous, sometimes puberulent; glands 4, crescent-shaped to triangular-ovate, 0.5–0.8 × 0.7–1.7 mm, margins usually entire, occasionally slightly crenate to dentate; horns divergent, 0.2–0.4 mm, longer than teeth on gland margin. |
campanulate, 1.5–2 × 1–1.5 mm, glabrous; glands 4, crescent-shaped to elliptic, 0.4–0.8 × 0.8–1.1 mm; horns divergent, 0.5–0.8 mm. |
Staminate flowers | 10–15. |
10–15. |
Pistillate flower(s) | ovary, usually glabrous, sometimes puberulent; styles 0.5–0.9 mm, 2-fid. |
ovary glabrous; styles 0.5–0.6 mm, 2-fid. |
Capsules | depressed-ovoid, 2.8–4 × 3.5–4.5 mm, 3-lobed; cocci rounded, smooth, usually glabrous, sometimes sparsely puberulent; columella 2.4–3.3 mm. |
ovoid-globose, 2–2.8 × 2.5–3 mm, 3-lobed; cocci rounded, smooth, glabrous; columella 1.6–2.1 mm. |
Seeds | light gray, cylindric ovoid-oblong, 2–2.8(–3) × 1.4–2.2 mm, irregularly shallowly pitted; caruncle sessile to shortly stipitate, conic, 0.4–0.5 × 0.8–1.1 mm. |
gray to purple-gray or sometimes nearly black, oblong, 1.3–1.6 × 0.9–1.2 mm, strongly small-pitted; caruncle umbonate, depressed-conic, 0.5 × 0.7 mm. |
Cyathial | arrangement: terminal pleiochasial branches 3–5(–8), 1–4+ times 2-branched; pleiochasial bracts lanceolate or ovate to broadly ovate, wider than distal leaves; dichasial bracts distinct, broadly ovate or rhombic to triangular-ovate, base obtuse, margins entire or slightly crenate, apex obtuse, mucronate; axillary cymose branches 0–8. |
arrangement: terminal pleiochasial branches 3, each many times 2-branched; pleiochasial bracts obovate, similar in size to distal leaves; dichasial bracts basally subconnate, strongly imbricate and often obscuring internodes, reniform to semiorbiculate, base cordate, margins entire, apex rounded; axillary cymose branches 0–5. |
Cyathia | peduncle 0.4–1 mm. |
peduncle 0.3–0.5 mm. |
2n | = 28. |
|
Euphorbia brachycera |
Euphorbia longicruris |
|
Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting spring. |
Habitat | Montane areas, canyons, rock crevices, sandy or gravelly slopes, pine-oak woodlands, ponderosa pine and mixed coniferous forests. | Grasslands, open prairies, sites with rocky, usually calcareous soils. |
Elevation | 1200–3200 m. (3900–10500 ft.) | 300–800 m. (1000–2600 ft.) |
Distribution |
AZ; CO; ID; MT; ND; NE; NM; SD; TX; UT; WY; Mexico (Chihuahua, Coahuila, Sonora)
|
AR; KS; OK; TX |
Discussion | Euphorbia brachycera is morphologically extremely variable, and plants from the northern part of the species range have sometimes been distinguished as E. robusta. Euphorbia brachycera is most closely related to the other native, perennial species of subg. Esula in western North America, namely E. chamaesula, E. lurida, E. schizoloba, and E. yaquiana. The name E. montana Engelmann, which has sometimes been applied to E. brachycera, is illegitimate because it is a later homonym of E. montana Rafinesque. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia longicruris is quite similar to the other small, annual members of subg. Esula in the south-central United States and can best be distinguished from those species by its imbricate dichasial bracts that form little tufts of overlapping leaves at the ends of the pleiochasial branches. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 300. | FNA vol. 12, p. 304. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | E. brachycera var. robusta, E. montana var. robusta, E. odontadenia, E. robusta, Tithymalus brachycerus, T. robustus | Tithymalus longicruris |
Name authority | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 192. (1859) | Scheele: Linnaea 22: 152. (1849) |
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