| Vernonia | |
|---|---|
 | |
| Vernonia baldwinii | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Subfamily: | Vernonioideae |
| Tribe: | Vernonieae |
| Genus: | Vernonia Schreb. |
| Species | |
| Synonyms[1] | |
List
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Vernonia is a genus of about 350species offorbs andshrubs in the familyAsteraceae.[1] Some species of this genus are known asironweeds. Some species are edible and ofeconomic value. They are known for having intensepurple flowers. There have been numerous distinct subgenera and subsections named in thisgenus, and some botanists have divided the genus into several distinct genera.[2][1] For instance, theFlora of North America recognizes only about twenty species inVernoniasensu stricto, seventeen of which are in North America north of Mexico, with the others being found inSouth America.[3]
The genus wascircumscribed byJohann Christian Daniel von Schreber inGen. Pl. ed. 8[a]. vol.2 on page 541 in 1791.[1]
The genus name ofVernonia is in honour of William Vernon (1666/67 - ca.1711), who was an English plant collector, (bryologist) andentomologist fromCambridge University, who collected inMaryland, USA in 1698.[4][5]
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Species of this genus are found inSouth America,Africa,Southeast Asia, andNorth America.Vernonia species are well known forhybridizing between similar species in areas of overlapping ranges. There are approximately 350 species in the genus.[1] A selected list is given below.
Several species ofVernonia, includingV. calvoana,V. amygdalina, andV. colorata, are eaten asleaf vegetables. Common names for these species includebitterleaf,onugbu in theIgbo language,ewuro andndole. They are common in mostWest African andCentral African countries. They are one of the most widely consumed leaf vegetables ofNigeria, where the onugbu soup is a local delicacy of theIgbo people, and ofCameroon, where they are a key ingredient ofNdolé: the national dish ofCameroon.[7] The leaves have a sweet and bitter taste. They are sold fresh ordried and are a typical ingredient inegusi soup.
Vernonia amygdalina is used in traditional herbal medicine. These leaves are exported from several African countries and can be purchased in grocery stores aiming to serve African clients. In Brazil,V. condensata is commonly known as "figatil" or "necroton" and used in local traditional medicine.[8]
Vernonia galamensis is used as anoilseed inEast Africa. It is grown in many parts ofEthiopia, especially around the city ofHarar, with an average seed yield of 2 to 2.5 t/ha. It is reported that the Ethiopian strains ofVernonia have the highest oil content, up to 41.9% with up to 80%vernolic acid, and is used in paint formulations, coatings plasticizers, and as a reagent for many industrial chemicals.[9]
Vernonia are grown asornamental plants in gardens, particularly some of the larger herbaceous North American species which are favoured for prairie-style plantings. The most widely grown areV. angustifolia,V. arkansana (syn.V. crinita),V. baldwinii,V. fasciculata,V. gigantea (syn.V. altissima),V. lettermannii,V. missurica andV. noveboracensis.[10]
A few cultivars have been selected, mostly on the basis of greater size and robustness (e.g.V. angustifolia 'Plum Peachy',V. gigantea 'Jonesboro Giant') or white flower colour (e.g.V. arkansana 'Alba',V. noveboracensis 'Albiflora',V. noveboracensis 'White Lightning').
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Vernonia species are used as food plants by thelarvae of someLepidoptera species includingColeophora vernoniaeella (which feeds exclusively on the genus) andSchinia regia (which feeds exclusively onV. texana).Vernonia is a very diverse genus, varying from the tinyV. desertorum of theCaatinga region ofBrazil which is only 8 cm (3.1 in) tall[11] toVernonia arborea of theEast Indies which, at 36 m (118 ft) is the tallest of allcomposites; a 472 fold difference in height. ThelianaVernonia andersoni ofBurma, according to Menninger, "climbs into the tops of trees"[12] and could be even taller. The leaves can vary from quite small up to 1.2 m (3 ft 11 in) long by up to 38 cm (15 in) in width in the case ofVernonia conferta ofCameroon.[13]