Euphorbia chamaesula |
Euphorbia vallis-mortae |
|
---|---|---|
mountain spurge |
Death Valley sandmat |
|
Habit | Herbs, perennial, with thick rootstock. | Herbs, perennial, with thickened, woody taproot. |
Stems | erect, branched, 40–90 cm, glabrous. |
prostrate to ascending, often mat-forming, 10–45 cm, pilose to villous. |
Leaves | petiole 0.5–1 mm; blade elliptic to oblong, 8–20(–40) × 3–6 mm, base truncate, rounded, or attenuate, margins entire, apex obtuse or acute, sometimes slightly mucronate, surfaces glabrous; venation inconspicuous, only midvein prominent. |
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 | turbinate or campanulate, 1.5–2.5 × 1.1–1.9 mm, glabrous; glands 4, crescent-shaped to semicircular, 0.5–0.8 × 1–1.8 mm; horns usually convergent, 0.2–0.8 mm. |
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 | 8–12. |
15–22(–50). |
Pistillate flowers | ovary glabrous; styles 1–1.8 mm, 2-fid. |
ovary densely pilose; styles 0.4–0.8 mm, 2-fid 1/2 length. |
Capsules | depressed-ovoid, 4.3–5 × 5–6 mm, 3-lobed; cocci rounded, smooth, glabrous; columella 3.5–4 mm. |
ovoid, 1.5–2.2 × 1.8–2.2 mm, tomentose; columella 1.2–1.6 mm. |
Seeds | gray to dark brown, ovoid-oblong, truncate at both ends, 2.6–3.4 × 2–2.6 mm, shallowly pitted to almost smooth; caruncle conic, 1 × 0.8 mm. |
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. |
Cyathial | arrangement: terminal pleiochasial branches 3–5(–6), each 3–4 times 2-branched; pleiochasial bracts ovate-lanceolate to slightly subpandurate, similar in size or wider than distal leaves; dichasial bracts distinct, lanceolate to broadly ovate, base usually truncate to rounded or subcordate, sometimes attenuate, margins entire or slightly crenulate, apex usually obtuse to acute, occasionally acuminate; axillary cymose branches 2–8. |
|
Cyathia | peduncle 1–3 mm. |
solitary at distal nodes; peduncle 0.5–1.8 mm. |
2n | = 26. |
|
Euphorbia chamaesula |
Euphorbia vallis-mortae |
|
Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting late spring–fall. |
Habitat | Clearings in ponderosa pine forests, montane roadsides, dry streambeds, creek banks, sandy and gravelly soils. | Roadsides, desert scrub, streamsides, sandy washes. |
Elevation | 1700–2700 m. (5600–8900 ft.) | 700–2000 m. (2300–6600 ft.) |
Distribution |
AZ; NM; Mexico (Chihuahua, Sonora)
|
CA |
Discussion | Euphorbia chamaesula is easily distinguished from other perennial members of subg. Esula in western North America by its larger capsules and the vegetative shoots (without cyathia) that arise from the distal nodes of the stem proximal to the pleiochasia. (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. 300. | FNA vol. 12, p. 291. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Tithymalus chamaesula | Chamaesyce vallis-mortae |
Name authority | Boissier: Cent. Euphorb., 38. (1860) | (Millspaugh) J. T. Howell: Madroño 2: 19. (1931) |
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