Euphorbia theriaca |
Euphorbia perennans |
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Terlingua sandmat, Terlingua spurge |
perennial sandmat, Terlingua spurge |
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Habit | Herbs, annual, with slender taproot. | Herbs, perennial, with strongly thickened, woody rootstock. | ||||
Stems | prostrate to reclining, not mat-forming, 5–30 cm, glabrous. |
erect, 7–45 cm, glabrous. |
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Leaves | opposite; stipules usually distinct, occasionally connate basally on lower side of stem, subulate or scalelike, usually entire, occasionally 2-fid or margin sparsely ciliate, 0.4–1 mm, glabrous; petiole 0.7–1.2(–1.5) mm, glabrous; blade ovate, oblong, orbiculate, or obovate, 2–7.1 × 1–3.5 mm, base slightly asymmetric, rounded, margins entire, often revolute on drying, apex usually rounded, occasionally slightly emarginate, surfaces glabrous; venation usually obscure, only midvein conspicuous. |
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. |
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Involucre | usually turbinate-campanulate to hemispheric, occasionally suburceolate, 1–1.8 × 0.9–1.4 mm, glabrous; glands 4, yellow-green to red-purple, sessile or short-stipitate, subcircular to slightly elliptic, 0.2–0.5 × 0.2–0.7 mm; appendages absent or white to pink, semilunate or forming rim at edge of gland, (0–)0.1–0.4 × (0–)0.3–0.9 mm, entire or slightly crenate. |
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. |
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Staminate flowers | 15–36. |
35–45. |
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Pistillate flowers | ovary glabrous; styles 0.3–0.5 mm, 2-fid 1/2 length. |
ovary glabrous; styles 0.7–0.9 mm, 2-fid nearly entire length. |
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Capsules | broadly ovoid, 1.1–1.6 × 1.5–1.8 mm, glabrous; columella 1.2–1.5 mm. |
subglobose to broadly ovoid, 2.8–3.3 × 2.8–3.4 mm, glabrous; columella 2.2–2.7 mm. |
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Seeds | whitish, reddish brown beneath coat, ovate, 4-angled in cross section, 0.8–1.2 × 0.5–0.8 mm, with (2–)3(–5) deep transverse ridges. |
white to light brown, ovoid, 3–4-angled in cross section, 2–2.4 × 1–1.2 mm, smooth to faintly transverse-wrinkled. |
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Cyathia | usually solitary at distal nodes, rarely clustered on short, axillary branches; peduncle 0.3–1.3 mm. |
solitary at distal nodes or at nodes of short, axillary branches; peduncle 1.8–3 mm. |
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2n | = 28. |
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Euphorbia theriaca |
Euphorbia perennans |
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Phenology | Flowering and fruiting spring–fall. | |||||
Habitat | Desert scrub, on cretaceous and gypseous clay, limestone hills and flats. | |||||
Elevation | 900–1200 m. (3000–3900 ft.) | |||||
Distribution |
NM; TX; n Mexico
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TX; Mexico (Chihuahua) |
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Discussion | Varieties 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
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Key |
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Source | FNA vol. 12, p. 290. | FNA vol. 12, p. 282. | ||||
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Chamaesyce theriaca | Chamaesyce perennans | ||||
Name authority | L. C. Wheeler: Rhodora 43: 242, plate 660, fig. A. (1941) | (Shinners) Warnock & M. C. Johnston: SouthW. Naturalist 5: 170. (1960) | ||||
Web links |