Euphorbia chaetocalyx |
Euphorbia texana |
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bristlecup sandmat |
Texas spurge |
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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. |
erect or ascending, unbranched or branched, sometimes extensively at crown, 7–20 cm, glabrous. |
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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. |
petiole 0–0.2 mm; blade oblanceolate to oblong-oblanceolate, 8–15 × 2–5 mm, base usually attenuate, occasionally cuneate, margins crenulate distally, apex rounded to obtuse, bluntly mucronate, surfaces glabrous; venation pinnate, midvein prominent. |
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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. |
hemispheric, 0.5–0.9 × 0.6–1 mm, glabrous; glands (4–)5, elongate reniform, 0.1–0.3 × 0.3–0.5 mm; horns absent. |
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Staminate flowers | 25–35. |
5. |
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Pistillate flowers | ovary glabrous; styles 0.3–0.4 mm, 2-fid 1/2 length. |
ovary glabrous; styles 0.8–1 mm, 2-fid. |
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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. |
depressed-globose, 1.6–2 × 2.5–3 mm, 3-lobed; cocci rounded, smooth, glabrous; columella 1.2–1.5 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. |
brownish black, globose-lenticular, 1.4–1.5 × 1.3–1.4 mm, finely reticulate or areolate with distinct line on back; caruncle low conic, 0.4 × 0.5 mm. |
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Cyathia | solitary at distal nodes; peduncle 0.8–1.3 mm. |
peduncle 0.3–0.6 mm. |
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Cyathial | arrangement: terminal pleiochasial branches 3, each 1–3 times 2-branched; pleiochasial bracts similar in shape and size to distal leaves; dichasial bracts distinct, elliptic to ovate, base acute to ± truncate, margins crenate distally, apex obtuse to rounded and mucronate; axillary cymose branches 1–3. |
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Euphorbia chaetocalyx |
Euphorbia texana |
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Phenology | Flowering and fruiting spring. | |||||
Habitat | Open ground, prairies. | |||||
Elevation | 0–200 m. (0–700 ft.) | |||||
Distribution |
AZ; NM; TX; n Mexico
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LA; TX |
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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 texana is related to E. alta and E. spathulata, but differs from both of those species in its smooth capsules. It is endemic to southeastern Texas and adjacent Louisiana. (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. 311. | ||||
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > subg. Esula | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | E. fendleri var. chaetocalyx, Chamaesyce chaetocalyx | E. dictyosperma var. leiococca, E. leiococca | ||||
Name authority | (Boissier) Tidestrom: Proc. Biol. Soc. Wash. 48: 40. (1935) | Boissier: Cent. Euphorb., 30. (1860) | ||||
Web links |