Euphorbia perennans |
Euphorbia cinerascens |
|
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perennial sandmat, Terlingua spurge |
ashy sandmat |
|
Habit | Herbs, perennial, with strongly thickened, woody rootstock. | Herbs, perennial, with moderately to strongly thickened rootstock. |
Stems | erect, 7–45 cm, glabrous. |
prostrate to decumbent, mat-forming, 5–30 cm, appressed wooly, strigillose, or short-sericeous. |
Leaves | opposite; stipules distinct, linear-filiform in (1–)2(–3) segments, 0.3–0.4 mm, glabrous; petiole 0.8–2 mm, glabrous; blade ovate or orbiculate-deltate to reniform-deltate, 5–17 × 4–16 mm midstem leaves largest, base symmetric, cuneate, rounded to cordate, margins entire, apex acute to rounded, surfaces glabrous, often glaucous; 3-veined from base, only midvein conspicuous. |
opposite; stipules distinct, subulate, 0.2–0.5 mm, appressed wooly to sericeous; petiole 0.3–0.8 mm, appressed wooly to sericeous; blade ovate to elliptic, 1.5–5.5 × 1.3–4 mm, base asymmetric, obtuse to hemicordate, margins entire often reddish, apex usually obtuse, occasionally acute (young leaves), surfaces sericeous to strigillose or slightly pilose, adaxial surface often glabrous; 3-veined from base but only midvein conspicuous. |
Involucre | broadly-campanulate to hemispheric, 1.7–2.2 × 1.5–2.7 mm, glabrous; glands 4, green to yellow-green, elliptic to oblong, folded longitudinally, 0.3–0.5 × 0.7–1.4 mm; appendages absent. |
turbinate, 0.8–1.3 × 1.2–2 mm, appressed wooly, sericeous, or strigillose; glands 4, purple-black, elliptic to oblong, 0.2–0.3 × 0.4–0.6 mm; appendages absent or reddish pink, forming narrow rim around distal margin of gland, 0–0.1 × 0–0.6 mm, distal margin entire, crenulate, or erose. |
Staminate flowers | 35–45. |
15–20. |
Pistillate flowers | ovary glabrous; styles 0.7–0.9 mm, 2-fid nearly entire length. |
ovary canescent; styles 0.3–0.5 mm, 2-fid at apex. |
Capsules | subglobose to broadly ovoid, 2.8–3.3 × 2.8–3.4 mm, glabrous; columella 2.2–2.7 mm. |
subglobose to broadly ovoid, 1.3–1.7 × 1.5–1.8 mm, canescent; columella 1–1.3 mm. |
Seeds | white to light brown, ovoid, 3–4-angled in cross section, 2–2.4 × 1–1.2 mm, smooth to faintly transverse-wrinkled. |
white to pinkish or light brown, ovoid, 4-angled in cross section, 1–1.4 × 0.6–0.8 mm, smooth to rugulose or rarely with 1–2 inconspicuous transverse ridges. |
Cyathia | solitary at distal nodes or at nodes of short, axillary branches; peduncle 1.8–3 mm. |
solitary at distal nodes; peduncle 0.2–0.3 mm. |
2n | = 32. |
|
Euphorbia perennans |
Euphorbia cinerascens |
|
Phenology | Flowering and fruiting spring–fall. | Flowering and fruiting year-round (mostly spring–fall). |
Habitat | Desert scrub, on cretaceous and gypseous clay, limestone hills and flats. | Desert scrub, oak and juniper woodlands, thorn scrub, shrublands, grasslands, frequently on limestone substrates. |
Elevation | 900–1200 m. (3000–3900 ft.) | 70–1400 m. (200–4600 ft.) |
Distribution |
TX; Mexico (Chihuahua) |
TX; Mexico |
Discussion | Euphorbia perennans is a distinctive species with an erect habit and relatively large, firm, deltate midstem leaves. Phylogenetic data place E. perennans in a clade of primarily Chihuahuan Desert annual and perennial species (for example, E. chaetocalyx, E. fendleri, E. golondrina, E. simulans, E. spurca, and E. theriaca; Y. Yang and P. E. Berry 2011). Euphorbia perennans is known in the flora area only from Brewster County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
In the flora area, Euphorbia cinerascens is found only in southern and western Texas. In Mexico, it is found from Chihuahua east to Tamaulipas, south to Guanajuato. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 282. | FNA vol. 12, p. 264. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Chamaesyce perennans | Chamaesyce cinerascens |
Name authority | (Shinners) Warnock & M. C. Johnston: SouthW. Naturalist 5: 170. (1960) | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 186. (1859) |
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