Annual or perennial herbs, shrubs or small trees, sometimes trailing or climbing, armed or unarmed, pubescent with glandular, simple or stellate hairs, rarely glabrous. Leaves usually alternate, sometimes paired, simple or pinnate, entire or lobed, petiolate. Inflorescences cyme-like, often scorpioid, terminal, lateral, axillary, pseudo-axillary or leaf-opposed, rarely reduced to a single flower. Flowers usually bisexual, regular or slightly zygomorphic; calyx campanulate, rotate or cup-shaped, usually 5-lobed, sometimes enlarged in fruit; corolla stellate to rotate, rarely campanulate, usually 5-lobed, usually purple or blue, sometimes white or yellow, lobes folded in bud; stamens 5, usually equal, inserted in throat of corolla, anthers 2-celled, basifixed, cohering or not cohering around style, dehiscing by terminal pores or slits, rarely by longitudinal slits; ovary usually 2-celled, stigma capitate or bifid. Fruit a succulent, cartilaginous or bony berry, sometimes enclosed by persistent inflated calyx; seeds suborbicular to lenticular, numerous.
About 1500 species, virtually cosmopolitan but mainly in Central and South America, also Africa and Australia; 117 species in Australia, 94 native, 87 endemic.
In many cases the presence of ripe fruit is necessary for reliable identification of species.
The South American garden Potato, Solanum tuberosum L., sometimes persists by tubers on farmland, in vegetable gardens, around rubbish tips or other places where garden refuse has been dumped, but is not truly naturalized in Victoria or elsewhere in Australia. Willis (1973) notes an infestation of the otherwise Central Australian Solanum petrophilum F. Muell. (Rock Nightshade) near Charlton in north-west Victoria, but it does not appear to have persisted there. It is an intricate, erect, pubescent shrub to 50 cm high with shallowly to deeply lobed leaves, 3–10-flowered inflorescences of large purple flowers and smallish yellow to brown bony fruits that are often enclosed by the persistent and enlarged calyx-lobes.
Bean, A.R. (2018). Solanum species of eastern and northern Australia, version 6 Sept. 2018, DELTA Intkey. https://www.delta-intkey.com/solanum/index.htm.