Euphorbia cuphosperma |
Euphorbia golondrina |
|
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hairy-fruit spurge |
Boquillas sandmat, canyon spurge, swallow spurge |
|
Habit | Herbs, annual, with taproot. | Herbs, annual, with slender taproot. |
Stems | erect, 13–20 cm, both pilose to villous and densely strigillose; branches ± straight. |
prostrate, 5–35 cm, glabrous. |
Leaves | usually opposite, occasionally alternate at distal nodes; petiole 3–15 mm, pilose; blade narrowly to broadly elliptic, or lanceolate to ovate, 30–80 × 10–15 mm, base cuneate to rounded, margins coarsely crenate-dentate, strigose, revolute to nearly flat, apex broadly acute to acuminate, or obtuse, abaxial surface pilose, adaxial surface sparsely strigose-hirsute; venation pinnate, midvein prominent. |
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. |
Involucre | campanulate to slightly cylindric, 2.3 × 1.2 mm, glabrous; involucral lobes divided into several linear, smooth lobes; gland 1, yellow-green, stipitate, clavate, 1–1.2 × 0.8–0.9 mm, opening bilabiate and oblong, glabrous; appendages absent. |
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. |
Staminate flowers | 3–5. |
28–40. |
Pistillate flowers | ovary pilose; styles 1.2 mm, 2-fid nearly entire length. |
ovary glabrous; styles 0.3–0.4 mm, 2-fid nearly entire length. |
Capsules | broadly ovoid, 2.2–3 × 1.9–2.7 mm, 3-lobed, pilose; columella 2–2.4 mm. |
broadly ovoid, 1.7–2 × 1.5–1.6 mm, glabrous; columella 1.4–1.7 mm. |
Seeds | gray-brown to pale gray, pyramidally ovoid, angular in cross section, 2.3–2.6 × 2.4–2.6 mm, coarsely tuberculate, tubercles in 2 transverse rows; caruncle 0.2–0.4 mm. |
narrowly pyramidal-ovoid, 4-angled in cross section, 1.3–1.5 × 0.6–0.7 mm, with very faint transverse ridges or wrinkles. |
Cyathial | arrangement: terminal pleiochasial branches usually 3, occasionally reduced to congested cyme, 1–2-branched; pleiochasial bracts 2–4, often whorled, wholly green or paler green at base, similar in shape and size to distal leaves or slightly narrower; dichasial bracts highly reduced. |
|
Cyathia | peduncle 0.5–0.8 mm. |
solitary at distal nodes; peduncle 0.9–1.5 mm. |
2n | = 56. |
|
Euphorbia cuphosperma |
Euphorbia golondrina |
|
Phenology | Flowering and fruiting summer–fall. | Flowering and fruiting late spring–fall. |
Habitat | Open montane and canyon forests, pinyon-juniper forests, montane grasslands, stream beds, disturbed habitats. | Deep, sandy riverbanks. |
Elevation | 800–2000 m. (2600–6600 ft.) | 600 m. (2000 ft.) |
Distribution |
AZ; NM; Mexico; Central America (Guatemala)
|
TX; Mexico (Chihuahua, Coahuila) |
Discussion | 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.) |
|
Source | FNA vol. 12, p. 319. | FNA vol. 12, p. 269. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | E. dentata var. cuphosperma, Poinsettia cuphosperma | Chamaesyce golondrina |
Name authority | (Engelmann) Boissier: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 15(2): 73. (1862) | L. C. Wheeler: Proc. Biol. Soc. Wash. 53: 8. (1940) |
Web links |