Euphorbia discoidalis |
Euphorbia vallis-mortae |
|
---|---|---|
summer spurge |
Death Valley sandmat |
|
Habit | Herbs, perennial, with spreading rootstock. | Herbs, perennial, with thickened, woody taproot. |
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 to ascending, often mat-forming, 10–45 cm, pilose to villous. |
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, subulate to filiform, 0.4–1.1 mm, densely tomentose; petiole 0.4–1 mm, pilose to villous; blade suborbiculate to oblong-ovate, 3–8 × 2–6 mm, base slightly asymmetric, rounded, margins entire, apex rounded to obtuse, surfaces pilose to villous; 3-veined at base, midvein conspicuous, venation often obscured by pubescence. |
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. |
obconic-campanulate, 1.2–2.3 × 1–1.8 mm, densely pilose to villous; glands 4, yellow to red, subcircular to oblong, 0.2–0.5 × 0.4–0.9 mm; appendages white, flabellate to oblong, 0.1–0.7 × 0.5–1.9 mm, distal margin entire or crenulate, adaxial surface ciliate-puberulent. |
Staminate flowers | 20–25. |
15–22(–50). |
Pistillate flowers | ovary glabrous or sparsely strigose; styles 0.5–1.1 mm, 2-fid at apex to 1/2 length. |
ovary densely pilose; styles 0.4–0.8 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. |
ovoid, 1.5–2.2 × 1.8–2.2 mm, tomentose; columella 1.2–1.6 mm. |
Seeds | light gray, ovoid, 2 × 1.2–1.3 mm, smooth or with few, very shallow depressions; caruncle absent. |
white, gray, or light brown, ovoid, sharply 4-angled in cross section, abaxial faces slightly convex, adaxial faces concave, 1.2–1.7 × 0.6–0.9 mm, smooth. |
Cyathia | in terminal pleiochasia; peduncle 5–15 mm, filiform, glabrous or very sparsely puberulent to sericeous. |
solitary at distal nodes; peduncle 0.5–1.8 mm. |
Euphorbia discoidalis |
Euphorbia vallis-mortae |
|
Phenology | Flowering and fruiting late spring–fall. | Flowering and fruiting late spring–fall. |
Habitat | Sand hills, pine savannas, woodland borders, open fields with sandy soils. | Roadsides, desert scrub, streamsides, sandy washes. |
Elevation | 0–150 m. (0–500 ft.) | 700–2000 m. (2300–6600 ft.) |
Distribution |
AL; FL; GA; LA; MS; TX
|
CA |
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.) |
The specific epithet of Euphorbia vallis-mortae is a misnomer because the species does not occur in Death Valley; instead, it is found at the transition of the northern edge of the Mojave Desert and the foothills of the southern Sierra Nevada in Inyo, Kern, and San Bernardino counties. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 245. | FNA vol. 12, p. 291. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Alectoroctonum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Tithymalopsis discoidalis | Chamaesyce vallis-mortae |
Name authority | Chapman: Fl. South. U.S., 401. (1860) | (Millspaugh) J. T. Howell: Madroño 2: 19. (1931) |
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