Euphorbia discoidalis |
Euphorbia velleriflora |
|
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summer spurge |
Caliche sandmat |
|
Habit | Herbs, perennial, with spreading rootstock. | Herbs, perennial, with strongly thickened and lignified rootstock. |
Stems | erect or ascending, unbranched, solitary or few, previous year's dead stems not persistent, 45–70 cm, usually densely puberulent to sericeous, rarely glabrous. |
prostrate, usually mat-forming, terete to slightly flattened and winged, to 30 cm, villous to pilose. |
Leaves | alternate; stipules to 0.1 mm; petiole (0–)1–2 mm (or absent), densely puberulent; blade usually linear, rarely ovate, 25–55 × 1.5–4 mm, base cuneate, margins entire, revolute, apex rounded, abaxial surface glabrous or puberulent to sericeous, adaxial surface glabrous; venation often obscure on smaller leaves, midvein conspicuous. |
opposite; stipules distinct or connate at base, 2-fid to laciniate into 2–5 linear to subulate divisions, 0.5–1(–2) mm, glabrous or villous; petiole 0.5–2 mm, villous; blade usually ovate to oblong, rarely suborbiculate, 5–13 × 4–8 mm, base asymmetric, hemicordate, margins serrulate, apex obtuse, surfaces villous; 3-veined from base, usually only midvein conspicuous. |
Involucre | campanulate, 1.2–1.4 × 1.2–2 mm, sparsely to densely puberulent; glands 5, green, reniform, 0.2–0.3 × 0.5–0.6 mm; appendages white, orbiculate to oblong, (0.5–)1–1.7 × 1–1.5 mm, entire. |
turbinate, 0.9–1.4 × 0.7–1.1 mm, villous; glands 4, pink, oblong to reniform, 0.1–0.2 × 0.3–0.4 mm; appendages white to pink, flabellate, ovate, or oblong, 0.3–0.5 × 0.4–0.7 mm, distal margin entire, crenulate, or erose, often puberulent-ciliate. |
Staminate flowers | 20–25. |
8–12. |
Pistillate flowers | ovary glabrous or sparsely strigose; styles 0.5–1.1 mm, 2-fid at apex to 1/2 length. |
ovary villous; styles 0.2–0.4(–0.5) mm, 2-fid 1/2 length. |
Capsules | globose, 1.8–3 × 2.5–4.8 mm, glabrous or sparsely strigose; columella 2.3–2.5 mm. |
broadly ovoid, 1.5–1.9 × 1.3–1.7 mm, villous (uniformly so, but most pronounced toward base and along keels); columella 1.2–1.4 mm. |
Seeds | light gray, ovoid, 2 × 1.2–1.3 mm, smooth or with few, very shallow depressions; caruncle absent. |
white to gray or pink, narrowly pyramidal-ovoid, 4-angled in cross section, 1.1–1.3 × 0.4–0.6 mm, rugulose with shallow depressions separated by inconspicuous transverse ridges. |
Cyathia | in terminal pleiochasia; peduncle 5–15 mm, filiform, glabrous or very sparsely puberulent to sericeous. |
solitary at distal nodes or at nodes of leafy, congested, axillary branches; peduncle 1–1.5(–2.5) mm. |
Euphorbia discoidalis |
Euphorbia velleriflora |
|
Phenology | Flowering and fruiting late spring–fall. | Flowering and fruiting summer. |
Habitat | Sand hills, pine savannas, woodland borders, open fields with sandy soils. | Disturbed habitats, particularly roadsides, grasslands, live oak-thorn scrub. |
Elevation | 0–150 m. (0–500 ft.) | 50–80 m. (200–300 ft.) |
Distribution |
AL; FL; GA; LA; MS; TX
|
TX; Mexico; Central America (Guatemala) [Introduced in North America] |
Discussion | M. J. Huft (1979) remarked that Euphorbia discoidalis is uncommon west of Alabama and referred many narrow-leaved specimens from Louisiana and Texas to E. corollata. K. R. Park (1998) included them in an expanded E. discoidalis, and that is followed here. The western populations can be distinguished from E. corollata by their shorter involucral gland appendages and revolute leaf margins. Further study of these western populations is warranted. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia velleriflora is native and widespread from northern Mexico to Guatemala. The species is apparently a recent introduction in southern Texas (W. R. Carr and M. H. Mayfield 1993), as the first records are from the 1990s. It is also expected in southern Arizona due to the presence of collections made a few kilometers south of the border in the Mexican state of Sonora. Euphorbia velleriflora is very similar to E. stictospora, and the two are sometimes confused. The two can be readily distinguished on the basis of their styles: unbranched in E. stictospora and 2-fid in E. velleriflora. Also, the involucral gland appendages of E. velleriflora are ciliate with short hairs, whereas those of E. stictospora are glabrous. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 245. | FNA vol. 12, p. 292. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Alectoroctonum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Tithymalopsis discoidalis | Anisophyllum velleriflorum, Chamaesyce velleriflora |
Name authority | Chapman: Fl. South. U.S., 401. (1860) | (Klotzsch & Garcke) Boissier: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 15(2): 40. (1862) |
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