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(Last Modified On 6/3/2013)
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(Last Modified On 6/3/2013)
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Species
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Vernonia cinerea (L.) Less.
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PlaceOfPublication
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Linnaea 4: 291. 1829.
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Synonym
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Conyza cinerea L., Sp. PI. 862. 1753. Seneciodes cinereum (L.) Kuntze in Post & Kuntze, Lex. Gen. Phan. 515. 1904.
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Description
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Herbs to 1 m tall, erect, unbranched to freely branched; branches striate, cinereous-puberulent above, glabrescent below. Leaves petiolate; petioles nar- rowly winged, 0.5-2.0 mm long; blades narrowly elliptic to deltoid, obtuse to acute at the apex, cuneate at the base, 2-5(-8) cm long, 0.5-3.0 cm broad, marginally entire to serrate, sparsely hirtellous above, glandular-punctate and hirtellous below, lateral veins ascending, 2-5 pairs. Inflorescences terminal, in dichoto- mously branched corymbs; peduncles 5-12 mm long; bracts often foliaceous, linear, to 1.5 cm long. Heads with 13-23 florets; involucre campanulate, the involucral bracts laxly 3-4-seriate, the outer bracts subulate, the inner bracts nar- rowly lanceolate, attenuate, puberulent; receptacle flat, alveolate, naked; corolla tubular, 3-4 mm long, 5-lobed, the lobes lanceolate, to 0.5 mm long; stamens 5, the anthers 0.6-0.8 mm long, apically acute, obtusely sagittate at the base; styles 3-4 mm long, with 2(3) branches to 0.5 mm long, rarely glabrous. Achenes sub- cylindric, ribless, 1.4-2.2 mm long, antrorsely puberulent; pappus biseriate, the inner bristles linear, 3-5 mm long, deciduous, the outer bristles subulate, to 0.5 mm long, persistent.
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Habit
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Herbs
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Note
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This species is readily distinguished in the field from the rest of the genus by the more delicate appearance of the inflorescences and the pedunculate heads. Found principally in disturbed areas such as clearings, road and railway margins, and in lawns, Vernonia cinerea is native of tropical areas of the Old World. It has become a pantropical weed through introductions into tropical America.
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Distribution
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extends northward into Mexico and in the United States into the Florida Keys and hammocks of extreme southern Florida.
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Specimen
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CANAL ZONE: Balboa, D'Arcy & D'Arcy 6020 (MO); Dwyer 2600 (MO). Atlantic side, just E of Gatun Locks, Duke 4299b, 4302 (both MO). Fort Sherman site, U.S. Army Tropic Test Center, Dwyer 7193 (MO). Howard Air Force Base, SE of Kobbe Beach, Oliver & MacBryde 1876 (OGH, MO, NY, US). Balboa Station, Porterfield s.n. (NY). Farfan Beach area, Tyson et al. 3181 (MO). BARRO COLORADO ISLAND: Aviles 90 (MO); Croat 4067, 6879 (both MO); Ebinger 131, 132 (both MO); Netting s.n. (MO); Shattuck 563 (MO); Starry 275 (MO). PANAMA: Bohio Soldada, Cowell 238 (NY). Morro Island, D'Arcy & D'Arcy 6809 (MO). Taboga Island, Dwyer 2786 (MO).
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