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Vernonia

(Genus)

Overview

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Perennials, 2-20(-30+) dm (rhizomatous or not) . Leaves usually mostly cauline (rarely mostly basal or basal and cauline) ; sessile or petiolate; blades ovate, elliptic, lanceolate, oblanceolate, spatulate, linear, or filiform, bases usually ± cuneate (rounded-truncate in V. pulchella), margins usually toothed (rarely entire), apices acute to attenuate, abaxial faces usually ± scabrellous to strigillose or tomentose to pannose, sometimes glabrate or glabrous, usually resin-gland-dotted (sometimes ± pitted), adaxial faces ± scabrellous or glabrate, sometimes resin-gland-dotted (rarely pitted) . Heads discoid, ± pedunculate, not subtended by foliaceous bracts, (6-) 40-100+ in ± corymbiform to paniculiform arrays (6-) 10-25+ cm diam. Involucres ± campanulate to obconic or hemispheric, 3-8(-11+) mm diam. Phyllaries 18-70+ in 4-7+ series, the outer ovate to lanceolate or subulate, inner ± lanceolate to oblong, all ± chartaceous, margins entire, often ciliolate, tips rounded (then sometimes apiculate), or acuminate, subulate, or filiform, faces glabrous or sparsely strigillose to tomentose, sometimes ± gland-dotted. Florets 9-30(-65+) ; corollas usually purplish or pink (rarely white), tubes longer than funnelform throats, lobes 5, lance-linear, ± equal. Cypselae ± columnar, sometimes arcuate, 8-10-ribbed, glabrous or ± strigillose to hirtellous, often resin-gland-dotted; pappi persistent, of 20-30+ outer, erose to subulate scales or bristles plus 20-40+ inner, longer, subulate to setiform scales or bristles. x = 17.

Species 20 or so: mainly c, e North America, n Mexico, 2-3 species in South America.

The circumscription of Vernonia adopted here follows that of H. Robinson (1999) .

Vernonias hybridize; almost every one of the species recognized here has been noted as sometimes hybridizing with one or more others. Putative hybrid plants are usually intermediate between parentals in some traits; such plants may not "key" satisfactorily to any of the species treated here. Some putative hybrids have been named. Vernonia guadalupensis is "without much doubt a hybrid of V. baldwinii Torrey and V. lindheimeri Engelmann & Gray" (L. H. Shinners 1950) ; V. vulturina Shinners (known only from the type collection) may be a product of V. baldwinii × V. marginata; V. ×georgiana Bartlett may refer to V. acaulis × V. angustifolia. Additional putative hybrids (S. B. Jones 1964) are V. ×concinna Gleason (V. ovalifolia × V. angustifolia), V. ×dissimilis Gleason (V. altissima × V. angustifolia), and V. ×recurva Gleason (V. pulchella × V. angustifolia) .[1]

Photos

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Taxonomy

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The Genus Vernonia is further organized into finer groupings including:

Bibliography

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Footnotes

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  1. John L. Strother "Vernonia". in Flora of North America Vol. 19, 20 and 21 Page 58, 67, 200, 201, 206, 207. Oxford University Press. Online at EFloras.org.

Sources

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Last Revised: October 04, 2013
2013/10/04 05:20:05