Euphorbia chaetocalyx |
Euphorbia laredana |
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bristlecup sandmat |
Laredo sandmat |
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Habit | Herbs, perennial, with woody, thickened taproot. | Herbs, annual, with taproot. | ||||
Stems | usually erect, rarely slightly decumbent, often densely clustered from top of woody crown, 3–15 cm, glabrous. |
prostrate, ± mat-forming, 10–20 cm, densely ashy pilose-tomentose. |
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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, filiform, 0.5–1 mm, pilose-tomentose; petiole 0.5–1 mm, pilose-tomentose; blade ovate to elliptic-oblong, 3–6 × 3–5 mm, base markedly asymmetric, rounded to slightly auriculate, margins usually entire, rarely largest leaves sparsely serrulate, apex acute to obtuse, surfaces moderately to densely strigose; 3-veined from base. |
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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, 0.6–1 × 0.5–1 mm, densely strigose; glands 4, yellowish to reddish, oval to oblong, 0.1 × 0.2–0.3 mm; appendages white to pink, rudimentary or minute, (0–)0.1–0.2 × (0–)0.1–0.3 mm, distal margin crenulate. |
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Staminate flowers | 25–35. |
3–5. |
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Pistillate flowers | ovary glabrous; styles 0.3–0.4 mm, 2-fid 1/2 length. |
ovary densely white villous; styles 0.1–0.2 mm, 2-fid 1/2 length. |
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Capsules | depressed-ovoid to depressed-globose, 1.7–2.1 × 1.6–2.4 mm, glabrous; columella 1.2–1.8 mm. |
broadly ovoid, 1.3–1.5 × 1.4–1.5 mm, villous on keels, often glabrous or less hairy between keels; columella 1.1–1.3 mm. |
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Seeds | white, ovoid-pyramidal, prominently 4-angled in cross section, 1.6–2 × 1–1.2 mm, smooth to slightly wrinkled. |
white, barely concealing brown undercoat, 4-angled, sharply angled in cross section, abaxial faces plane to convex, adaxial faces concave, 1.1–1.2 × 0.5–0.7 mm, with several rounded, irregular, transverse ridges. |
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Cyathia | solitary at distal nodes; peduncle 0.8–1.3 mm. |
solitary or in small, cymose clusters at distal nodes or on congested, axillary branches; peduncle 0.5–1.5 mm. |
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Euphorbia chaetocalyx |
Euphorbia laredana |
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Phenology | Flowering and fruiting almost year-round. | |||||
Habitat | Open sandy, loamy, or gravelly sites, old dunes, pastures. | |||||
Elevation | 0–200 m. (0–700 ft.) | |||||
Distribution |
AZ; NM; TX; n Mexico
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TX; Mexico (Tamaulipas) |
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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.) |
Euphorbia laredana is similar to E. prostrata but differs from that species in its more densely tomentose indumentum, leaves with usually entire rather than serrulate margins, and slightly longer seeds with rounded rather than sharp ridges. The species occurs primarily in southern Texas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 12, p. 263. | FNA vol. 12, p. 274. | ||||
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | E. fendleri var. chaetocalyx, Chamaesyce chaetocalyx | Chamaesyce laredana | ||||
Name authority | (Boissier) Tidestrom: Proc. Biol. Soc. Wash. 48: 40. (1935) | Millspaugh: Pittonia 2: 88. (1890) | ||||
Web links |