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(Last Modified On 6/3/2013)
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(Last Modified On 6/3/2013)
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Genus
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Vernonia Schreb.
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PlaceOfPublication
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Gen. P1. 2: 541. 1791, nom. cons.
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Note
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TYPE: V. noveboracensis (L.) Willd.
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Synonym
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Seneciodes Post & Kuntze, Lex. Gen. Phan. 2: 515. 1903. Eremosis (DC.) Gleason, Bull. New York Bot. Gard. 4: 227. 1906.
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Description
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Annual or perennial herbs, shrubs, or trees, rarely scandent, unbranched to much-branched; branches usually ascending, variously pubescent to glabrous. Leaves alternate, simple, usually cauline; blades various, often narrowly lanceolate to broadly ovate or elliptic. Inflorescences terminal or upper axillary, composed of scorpioid cymes or becoming paniculate or corymbiform or rarely reduced to solitary heads. Heads discoid with 1-many florets; involucre narrowly campan- ulate to subcylindric to broadly hemispheric, the involucral bracts in few to many series, closely to laxly imbricate, the inner series often longer, persistent and spreading at maturity; receptacle flat or subconvex; corolla regular, usually pink, purple, or white, 5-lobed; stamens 5, the anthers sagittate at the base, rounded or subacute at the apex, appendaged. Achenes more or less cylindric, ribbed or ribless; pappus of slender bristles or scales, biseriate, the inner series capillary, terete to slightly flattened, the outer series very short.
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Habit
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herbs, shrubs, or trees
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Note
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This large genus of perhaps 550-600 species inhabits primarily tropical regions of both the Old and New Worlds. In the New World, Vernonia is most abundant in South America, but extends northward through Central America into temperate North America. Six species are recognized from Panama including the naturalized Old World species, V. cinerea.
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Distribution
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known from British Honduras, Honduras, Nicaragua, and tropical South America
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Note
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suspected to occur in Panama.
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Reference
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Gleason, H. A. 1906. A revision of the North American Vernonieae. Bull. New York Bot. Gard. 4: 144-243. Gleason, H A. 1922. Vernonia and Eremosis. In North American Flora 3: 52-101. Jones, S. B., Jr. 1973. Revision of Vernonia sect. Eremosis (Compositae) in North America. Brittonia 25: 86-115.
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Key
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a. Heads with 13-36 florets. b. Heads pedunculate, the peduncles 5-12 mm long; inflorescences corymbose, the axes equal, strongly dichotomizing; achenes ribless; leaves with 2-4 pairs of lateral veins; bristles of the inner pappu...... 3. V. cinerea bb. Heads sessile, subsessile, or short-pedunculate; inflorescences paniculate or corymbose, the axes unequal, sometimes monopodial; achenes ribbed; leaves with 5-20 pairs of lateral veins; bristles of the inner pappus persistent. c. Heads subtended by foliaceous bracts 10-15 mm long; heads with 24-36 florets; involucre 6-8 mm tall, 6-7-seriate ...... 5. V. seemanniana cc. Heads without foliaceous bracts or with only subulate bracts; heads with 18-27 florets; involucre 3-6 mm tall, 4-6-seriate. d. Inflorescence a sparsely or freely branched cyme; leaves broadly elliptic to broadly ovate. e. Leaves broadly elliptic to broadly ovate, 10-30 cm long, 5-13 cm broad, subauriculate at the base, plane and glabrous to glabrescent above; inflorescences with the individual cymes usually recurved and with 22-46 heads ...... 1. V. brachiata ee. Leaves broadly lanceolate to ovate-elliptic, 3-15 cm long, 1-5 cm broad, rounded to obtuse at the base, rugose to rarely bullate and scabrous to strigillose above; inflorescences with the individual cymes spreading and with 18 heads or fewer ...... 2. V. canescens dd. Inflorescence a much-branched corymb or panicle; leaves lanceolate ...... 4. V. patens aa. Heads with 3-4 florets ...... 6. V. triflosculosa
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