Euphorbia albomarginata |
Euphorbia texana |
|
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rattlesnake sandmat, rattlesnake weed, white-margin sandmat or sandwort, whitemargin sandmat |
Texas spurge |
|
Habit | Herbs, perennial, with moderately to strongly thickened rootstock. | Herbs, annual, with taproot. |
Stems | prostrate, occasionally mat-forming, frequently rooting at nodes, 10–80 cm, glabrous. |
erect or ascending, unbranched or branched, sometimes extensively at crown, 7–20 cm, glabrous. |
Leaves | opposite; stipules connate into conspicuous, deltate or ovate scale, white, 0.4–1(–2) mm, glabrous; petiole less than 1 mm, glabrous; blade ovate, oblong or orbiculate, 3–8(–15) × 3–7 mm, base strongly asymmetric, obtuse to hemicordate, margins whitish, entire, apex obtuse, rarely mucronulate, surfaces often with red blotch in center, glabrous; 3-veined from base but usually only midvein conspicuous. |
petiole 0–0.2 mm; blade oblanceolate to oblong-oblanceolate, 8–15 × 2–5 mm, base usually attenuate, occasionally cuneate, margins crenulate distally, apex rounded to obtuse, bluntly mucronate, surfaces glabrous; venation pinnate, midvein prominent. |
Involucre | campanulate, 0.8–1.1 × 0.9–2 mm, glabrous; glands 4, greenish yellow to red, usually oblong to reniform, rarely subcircular, 0.2–0.5 × (0.2–)0.3–0.8 mm; appendages white to pink, flabellate to oblong, 0.3–1 × 0.6–1.3 mm, distal margin entire or crenulate to erose. |
hemispheric, 0.5–0.9 × 0.6–1 mm, glabrous; glands (4–)5, elongate reniform, 0.1–0.3 × 0.3–0.5 mm; horns absent. |
Staminate flowers | 15–30. |
5. |
Pistillate flowers | ovary glabrous; styles 0.3–0.7 mm, 2-fid nearly entire length. |
ovary glabrous; styles 0.8–1 mm, 2-fid. |
Capsules | broadly ovoid, 1.1–2.3 × 1.2–2 mm, glabrous; columella 1.1–1.6 mm. |
depressed-globose, 1.6–2 × 2.5–3 mm, 3-lobed; cocci rounded, smooth, glabrous; columella 1.2–1.5 mm. |
Seeds | white to gray or brownish red, oblong-ovoid, 4-angled in cross section, 1–1.7 × 0.5–0.8 mm, smooth. |
brownish black, globose-lenticular, 1.4–1.5 × 1.3–1.4 mm, finely reticulate or areolate with distinct line on back; caruncle low conic, 0.4 × 0.5 mm. |
Cyathia | solitary at distal nodes; peduncle 1–4 mm. |
peduncle 0.3–0.6 mm. |
Cyathial | arrangement: terminal pleiochasial branches 3, each 1–3 times 2-branched; pleiochasial bracts similar in shape and size to distal leaves; dichasial bracts distinct, elliptic to ovate, base acute to ± truncate, margins crenate distally, apex obtuse to rounded and mucronate; axillary cymose branches 1–3. |
|
Euphorbia albomarginata |
Euphorbia texana |
|
Phenology | Flowering and fruiting year-round. | Flowering and fruiting spring. |
Habitat | Disturbed areas in desert scrub, grasslands, mesquite woodlands, chaparral. | Open ground, prairies. |
Elevation | 0–2300 m. (0–7500 ft.) | 0–200 m. (0–700 ft.) |
Distribution |
AZ; CA; CO; NM; NV; OK; TX; UT; Mexico [Introduced in Pacific Islands (Hawaii)]
|
LA; TX |
Discussion | Euphorbia albomarginata is native to northern and central Mexico and the southwestern and south-central United States. The species occurs in a variety of habitats in western North America and in some areas is quite weedy. It has been recorded as a waif in Louisiana. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia texana is related to E. alta and E. spathulata, but differs from both of those species in its smooth capsules. It is endemic to southeastern Texas and adjacent Louisiana. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 259. | FNA vol. 12, p. 311. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | Chamaesyce albomarginata | E. dictyosperma var. leiococca, E. leiococca |
Name authority | Torrey & A. Gray: in War Department [U.S.], Pacif. Railr. Rep. 2(4): 174. (1857) | Boissier: Cent. Euphorb., 30. (1860) |
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