Solanum

Solanum is a large and diverse genus of flowering plants, which include three food crops of high economic importance: the potato, the tomato and the eggplant (aubergine, brinjal). It also contains the nightshades and horse nettles, as well as numerous plants cultivated for their ornamental flowers and fruit.
"Solanum" species show a wide range of growing habits, such as annuals and perennials, vines, subshrubs, shrubs, and small trees. Many formerly independent genera like "Lycopersicon" (the tomatoes) and "Cyphomandra" are now included in "Solanum" as subgenera or sections. Thus, the genus today contains roughly 1,500–2,000 species.
Name.
The generic name was first used by Pliny the Elder (AD 23–79) for a plant also known as , most likely "S. nigrum". Its derivation is uncertain, possibly stemming from the Latin word , meaning "sun", referring to its status as a plant of the sun.
Nightshades.
The species most commonly called nightshade in North America and Britain is "Solanum dulcamara", also called bittersweet or woody nightshade. Its foliage and egg-shaped red berries are poisonous, the active principle being solanine, which can cause convulsions and death if taken in large doses. The black nightshade ("S. nigrum") is also generally considered poisonous, but its fully ripened fruit and foliage are cooked and eaten in some areas. The deadly nightshade ("Atropa belladonna") is not in the genus "Solanum", but is a member of the family Solanaceae.
Food crops.
Most parts of the plants, especially the green parts and unripe fruit, are poisonous to humans (although not necessarily to other animals), but many species in the genus bear some edible parts, such as fruits, leaves, or tubers. Three crops in particular have been bred and harvested for consumption by humans for centuries, and are now cultivated on a global scale:
Other species are significant food crops regionally, such as Ethiopian eggplant or gilo ("S. aethiopicum"), naranjilla or lulo ("S. quitoense"), Turkey berry ("S. torvum"), pepino or pepino melon ("S. muricatum"), Tamarillo ("S. betaceum"), wolf apple (S. lycocarpum), garden huckleberry ("S. scabrum") and "bush tomatoes" (several Australian species).
Ornamentals.
The species most widely seen in cultivation as ornamental plants are:
Medicine.
Poisonings associated with certain species of "Solanum" are not uncommon and may be fatal. However, several species are locally used in folk medicine, particularly by native people who have long employed them.
Ecology.
"Solanum" species are used as food plants by the larvae of some Lepidoptera species (butterflies and moths) – see list of Lepidoptera that feed on "Solanum".
Systematics.
The genus was established by Carl Linnaeus in 1753. Its subdivision has always been problematic, but slowly some sort of consensus is being achieved.
The following list is a provisional lineup of the genus' traditional subdivisions, together with some notable species. Many of the subgenera and sections might not be valid; they are used here provisionally as the phylogeny of this genus is not fully resolved yet and many species have not been reevaluated.
Cladistic analyses of DNA sequence data suggest that the present subdivisions and rankings are largely invalid. Far more subgenera would seem to warrant recognition, with "Leptostemonum" being the only one that can at present be clearly subdivided into sections. Notably, it includes as a major lineage several members of the traditional sections "Cyphomandropsis" and the old genus "Cyphomandra".
Subgenus "Bassovia".
Section "Allophylla"
Section "Cyphomandropsis"
Section "Pachyphylla"
Subgenus "Leptostemonum".
Section "Acanthophora"
Section "Androceras": 12 spp.
Section "Anisantherum"
Section "Campanulata"
Section "Crinitum"
Section "Croatianum"
Section "Erythrotrichum"
Section "Graciliflorum"
Section "Herposolanum"
Section "Irenosolanum"
Section "Ischyracanthum"
Section "Lasiocarpa"
Section "Melongena"
Section "Micracantha"
Section "Monodolichopus"
Section "Nycterium"
Section "Oliganthes"
Section "Persicariae"
Section "Polytrichum"
Section "Pugiunculifera"
Section "Somalanum"
Section "Torva"
Subgenus "Solanum sensu stricto".
Section "Afrosolanum"
Section "Anarrhichomenum"
Section "Archaesolanum"
Section "Basarthrum"
Section "Benderianum"
Section "Brevantherum"
Section "Dulcamara"
Section "Herpystichum"
Section "Holophylla"
Section "Juglandifolia"
Section "Lemurisolanum"
Section "Lycopersicoides"
Section "Lycopersicon"
Section "Macronesiotes"
Section "Normania"
Section "Petota"
Section "Pteroidea"
Section "Quadrangulare"
Section "Regmandra"
Section "Solanum"
Formerly placed here.
Some plants of other genera were formerly placed in "Solanum":