Euphorbia hexagona |
Euphorbia chaetocalyx |
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six-angle spurge |
bristlecup sandmat |
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Habit | Herbs, annual, with taproot. | Herbs, perennial, with woody, thickened taproot. | ||||
Stems | erect, unbranched or branched, 30–70(–100) cm, sparsely hispid, occasionally densely so at distal nodes. |
usually erect, rarely slightly decumbent, often densely clustered from top of woody crown, 3–15 cm, glabrous. |
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Leaves | opposite; stipules (0–)0.1 mm; petiole 1–4 mm, pilose; blade linear-filiform, linear, or elliptic, 21–40 × 0.9–7.5 mm, base attenuate, margins entire, apex acute, abaxial surface sparsely hispidulous to strigillose, adaxial surface glabrous; venation obscure, only midvein conspicuous. |
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. |
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Involucre | campanulate, 1–1.5 × (1–)1.5–1.8 mm, hispid; glands 5, green to deep red, elliptic to reniform, 0.5 × 0.8–1 mm; appendages white to green, tinged red, deltate to ovate, 0.7–1.7 × (0.9–)1.3–1.5 mm, entire. |
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. |
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Staminate flowers | 15–30(–40). |
25–35. |
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Pistillate flowers | ovary glabrous; styles 0.7–1.1 mm, 2-fid nearly entire length. |
ovary glabrous; styles 0.3–0.4 mm, 2-fid 1/2 length. |
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Capsules | subglobose to broadly ovoid, 4.7–6.5 × 4.9–6.5(–7.1) mm, glabrous; columella 3.5–4.5 mm. |
depressed-ovoid to depressed-globose, 1.7–2.1 × 1.6–2.4 mm, glabrous; columella 1.2–1.8 mm. |
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Seeds | dark brown or dark gray, ovoid, 3.4 × 2.7 mm, rugose, whitish glaucous; caruncle absent. |
white, ovoid-pyramidal, prominently 4-angled in cross section, 1.6–2 × 1–1.2 mm, smooth to slightly wrinkled. |
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Cyathia | solitary in leaf axils or in terminal cymes or dichasia; peduncle 1–2.1 mm, strigillose. |
solitary at distal nodes; peduncle 0.8–1.3 mm. |
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Euphorbia hexagona |
Euphorbia chaetocalyx |
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Phenology | Flowering and fruiting late summer–fall. | |||||
Habitat | Sand prairies, other sandy soil habitats, stream banks, sand bars, damp places. | |||||
Elevation | 200–1300 m. (700–4300 ft.) | |||||
Distribution |
AR; CO; IA; IL; KS; MN; MO; MT; NE; NM; OK; SD; TX; WI; WY
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AZ; NM; TX; n Mexico
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Discussion | Euphorbia hexagona is native to the central United States and is most common from southern South Dakota to Oklahoma and northern Texas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
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Key |
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Source | FNA vol. 12, p. 247. | FNA vol. 12, p. 263. | ||||
Parent taxa | Euphorbiaceae > Euphorbia > sect. Alectoroctonum | Euphorbiaceae > Euphorbia > sect. Anisophyllum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | E. fendleri var. chaetocalyx, Chamaesyce chaetocalyx | |||||
Name authority | Nuttall ex Sprengel: Syst. Veg. 3: 791. (1826) | (Boissier) Tidestrom: Proc. Biol. Soc. Wash. 48: 40. (1935) | ||||
Web links |