Euphorbia theriaca |
Euphorbia golondrina |
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Terlingua sandmat, Terlingua spurge |
Boquillas sandmat, canyon spurge, swallow spurge |
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Habit | Herbs, annual, with slender taproot. | Herbs, annual, with slender taproot. | ||||
Stems | prostrate to reclining, not mat-forming, 5–30 cm, glabrous. |
prostrate, 5–35 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, subulate, 0.5–0.8 mm, glabrous; petiole 0.8–1 mm, glabrous; blade oblong, ovate-oblong, to narrowly elliptic-oblong, 5–11.5 × 1–4 mm, base asymmetric, cuneate to rounded, margins entire, thickened and often revolute on drying, apex obtuse, surfaces glabrous; 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. |
turbinate, 0.9–1.5 × 0.8–1.3 mm, glabrous; glands 4, occasionally rudimentary, red to purple, deeply concave, subcircular, 0.3–0.4 × 0.3–0.4 mm; appendages white, semilunate to slightly flabellate, 0.1–0.3 × 0.5–0.8 mm, distal margin entire. |
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Staminate flowers | 15–36. |
28–40. |
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Pistillate flowers | ovary glabrous; styles 0.3–0.5 mm, 2-fid 1/2 length. |
ovary glabrous; styles 0.3–0.4 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. |
broadly ovoid, 1.7–2 × 1.5–1.6 mm, glabrous; columella 1.4–1.7 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. |
narrowly pyramidal-ovoid, 4-angled in cross section, 1.3–1.5 × 0.6–0.7 mm, with very faint transverse ridges or wrinkles. |
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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; peduncle 0.9–1.5 mm. |
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2n | = 28. |
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Euphorbia theriaca |
Euphorbia golondrina |
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Phenology | Flowering and fruiting late spring–fall. | |||||
Habitat | Deep, sandy riverbanks. | |||||
Elevation | 600 m. (2000 ft.) | |||||
Distribution |
NM; TX; n Mexico
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TX; Mexico (Chihuahua, Coahuila) |
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Discussion | Varieties 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia golondrina was first collected on a sandy riverbank at the entrance of Boquillas Canyon on the Texas/Mexico border, and the species appears to be restricted to the vicinity of the Rio Grande in western Texas and northern Mexico. Aside from the type locality at Boquillas Canyon, E. golondrina has been documented from additional locations along the Rio Grande in Brewster, Hudspeth, and Presidio counties in Texas and from northern Coahuila and Chihuahua, Mexico. Phylogenetic data place E. golondrina in a clade of primarily Chihuahuan desert annual and perennial herbaceous species (for example, E. chaetocalyx, E. fendleri, E. perennans, E. simulans, E. spurca, and E theriaca; Y. Yang and P. E. Berry 2011). Euphorbia golondrina is superficially similar to other glabrous species in western Texas (for example, E. micromera and E. theriaca), but E. micromera and E. theriaca either lack involucral gland appendages or have shorter, triangular appendages compared to the typical semilunate appendages in E. golondrina. (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. 269. | ||||
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Chamaesyce theriaca | Chamaesyce golondrina | ||||
Name authority | L. C. Wheeler: Rhodora 43: 242, plate 660, fig. A. (1941) | L. C. Wheeler: Proc. Biol. Soc. Wash. 53: 8. (1940) | ||||
Web links |