Xanthium spinosum |
Xanthium |
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clotbur, lampourde épineuse, spiny clotbur, spiny cocklebur, spiny cockleburr |
cocklebur, lampourde |
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Habit | Plants 10–60(–120+) cm; nodal spines usually in pairs, simple or 2–3-partite, 15–30+ mm. | Annuals (coarse), 10–200+ cm. | ||||
Stems | erect, branched. |
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Leaves | petioles 1–15(–25+) mm; blades ± ovate to lanceolate or lance-linear, 4–8(–12+) × 1–3(–5+) cm, often pinnately 3(–7+)-lobed, abaxial faces gray to white, densely strigose. |
cauline; mostly alternate (proximal 2–6 sometimes opposite); petiolate; blades lanceolate, linear, ovate, rounded-deltate, or suborbiculate, often ± palmately or pinnately lobed, ultimate margins entire or ± toothed, faces hirtellous or ± strigose, usually gland-dotted as well. |
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Staminate heads | involucres ± saucer-shaped, 3–5 mm diam.; phyllaries 6–16+ in 1–2+ series, distinct to bases; receptacles conic to columnar; paleae spatulate to cuneiform or linear, membranous, distally ± villous or hirtellous; florets 20–50+, corollas whitish, ± funnelform, lobes 5, erect or reflexed (filaments connate, anthers distinct or weakly coherent). |
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Pistillate heads | involucres ± ellipsoid, 2–5+ mm diam. at anthesis (6–20+ mm diam. at maturity); phyllaries 30–75+ in 6–12+ series, outer 5–8 distinct, the rest (sometimes interpreted as paleae) proximally connate, their distinct tips mostly ± hooked (the distal 1–3 usually longer, stouter, and not hooked), the whole becoming a hard, prickly perigynium (a bur); florets 2, corollas 0. |
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Heads | discoid, either pistillate (proximal) or functionally staminate (distal), in racemiform to spiciform arrays or borne singly (in axils). |
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Cypselae | (black) ± fusiform, enclosed in obovoid to ellipsoid, hard, prickly, 2-chambered burs; pappi 0. |
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Burs | 10–12(–15+) mm. |
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x | = 18. |
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2n | = 36. |
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Xanthium spinosum |
Xanthium |
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Phenology | Flowering Jul–Oct. | |||||
Habitat | Damp or seasonally wet, alkaline soils, waste places, margins of agriculture | |||||
Elevation | 10–1000 m (0–3300 ft) | |||||
Distribution |
AL; AZ; CA; CO; CT; DE; FL; GA; IA; ID; IL; IN; KS; KY; MA; MD; ME; MI; MO; MS; MT; NC; NE; NH; NJ; NM; NV; NY; OH; OR; PA; RI; SC; TN; TX; UT; VA; WA; WV; NB; ON; QC; SK; Mexico; Central America; South America; widely established in Old World
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New World; introduced nearly worldwide |
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Discussion | Some authors have contended that Xanthium spinosum originated in South America and is introduced and/or naturalized everywhere else that it is found. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Species 2–3 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 21, p. 19. | FNA vol. 21, p. 19. | ||||
Parent taxa | Asteraceae > tribe Heliantheae > subtribe Ambrosiinae > Xanthium | Asteraceae > tribe Heliantheae > subtribe Ambrosiinae | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | X. ambrosioides, X. spinosum var. inerme | |||||
Name authority | Linnaeus: Sp. Pl. 2: 987. (1753) | Linnaeus: Sp. Pl. 2: 987. (1753): Gen. Pl. ed. 5, 424. (1754) | ||||
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