Euphorbia chaetocalyx |
Euphorbia vallis-mortae |
|||||
---|---|---|---|---|---|---|
bristlecup sandmat |
Death Valley sandmat |
|||||
Habit | Herbs, perennial, with woody, thickened taproot. | Herbs, perennial, with thickened, woody taproot. | ||||
Stems | usually erect, rarely slightly decumbent, often densely clustered from top of woody crown, 3–15 cm, glabrous. |
prostrate to ascending, often mat-forming, 10–45 cm, pilose to villous. |
||||
Leaves | opposite; stipules distinct, narrowly linear, usually entire, 0.5–1 mm, glabrous; petiole 0.5–1 mm, glabrous; blade ovate to lanceolate or oblong- or linear-lanceolate, 3–11 × 0.8–3(–5) mm, base slightly asymmetric, short-tapered, occasionally one side slightly rounded, margins entire, apex acute or short-acuminate, surfaces glabrous; only 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 to turbinate, 0.8–1.4 × 0.8–1 mm, glabrous; glands 4, yellow-brown to reddish, concave or convex, elliptic or oval, 0.2–0.4 × 0.4–0.6 mm; appendages absent or white, lanceolate-deltate to straplike, 0.2–1.1 × 0.2–0.9 mm, distal margin entire, crenate, or deeply cleft or divided. |
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 | 25–35. |
15–22(–50). |
||||
Pistillate flowers | ovary glabrous; styles 0.3–0.4 mm, 2-fid 1/2 length. |
ovary densely pilose; styles 0.4–0.8 mm, 2-fid 1/2 length. |
||||
Capsules | depressed-ovoid to depressed-globose, 1.7–2.1 × 1.6–2.4 mm, glabrous; columella 1.2–1.8 mm. |
ovoid, 1.5–2.2 × 1.8–2.2 mm, tomentose; columella 1.2–1.6 mm. |
||||
Seeds | white, ovoid-pyramidal, prominently 4-angled in cross section, 1.6–2 × 1–1.2 mm, smooth to slightly wrinkled. |
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 | solitary at distal nodes; peduncle 0.8–1.3 mm. |
solitary at distal nodes; peduncle 0.5–1.8 mm. |
||||
Euphorbia chaetocalyx |
Euphorbia vallis-mortae |
|||||
Phenology | Flowering and fruiting late spring–fall. | |||||
Habitat | Roadsides, desert scrub, streamsides, sandy washes. | |||||
Elevation | 700–2000 m. (2300–6600 ft.) | |||||
Distribution |
AZ; NM; TX; n Mexico
|
CA |
||||
Discussion | Varieties 2 (2 in the flora). Euphorbia chaetocalyx is similar to E. fendleri but can generally be distinguished from that species by its narrow, acute leaves and ± erect stems. Some authors have used the presence or absence and shape of the involucral gland appendages to help separate E. chaetocalyx from E. fendleri, but those characters appear highly variable and of little taxonomic utility. Some individuals from western Texas (Culberson and El Paso counties) and southern New Mexico appear intermediate with E. fendleri. The specific epithet of E. chaetocalyx refers to the bristly perianthlike segments that subtend the ovary, but these structures are found intermittently in both E. chaetocalyx and E. fendleri. (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.) |
||||
Key |
|
|||||
Source | FNA vol. 12, p. 263. | FNA vol. 12, p. 291. | ||||
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | E. fendleri var. chaetocalyx, Chamaesyce chaetocalyx | Chamaesyce vallis-mortae | ||||
Name authority | (Boissier) Tidestrom: Proc. Biol. Soc. Wash. 48: 40. (1935) | (Millspaugh) J. T. Howell: Madroño 2: 19. (1931) | ||||
Web links |