Australia has around 100 species of the Solanum genus which are endemic to the continent. There are also another 20 odd species which are well established and are considered introduced weeds. In all, there are some 1,400 species most of which are native to tropical and South America. The Solanum genus includes the potato, tomato and eggplant. The many varieties of nightshade are also found in this genus. Some parts of some species are poisonous to humans.
The solanum may be deciduous or evergreen. Many have prickles. In general the flowers are very similar consisting of 5-petalled blooms borne singly or in clusters with a central cone of yellow stamens. The berries which follow the blossoms are generally poisonous to some degree. Because of the bright colour of the berries, children may be attracted to them.
One species which has edible berries is Solanum ellipticum. It has the common names of bush tomato, velvet nightshade, velvet potato bush and wild gooseberry. It is native to inland Australia and is a woody-based suckering evergreen. The branches are low, hairy and prickly. The dark, blue-green leaves have prominent veins. It produces racemes of 3 to 7 purple or blue flowers with yellow centres. The flowers are followed by greenish berries.
Solanum centrale is also called the desert (or bush raisin). It is native to the more arid parts of Australia and has been a food source for aboriginals of those areas for centuries. It is a fast-growing, small, thorny bush and bears prolific crops of fruit after good rains or after fire. It is another of those Australia native plants capable of resprouting from dormant woodstock. The fruits are rich in vitamin C and 1 to 3cm in diameter. When fully ripe, they are yellow in colour. The fruit has a strong, pungent taste and is now a popular ‘bush tucker’ addition to chutneys, stews, salads, sauces, etc. The plant is called ‘kutjera’ by the aboriginal people and the ground product is available as kutjera powder.
Solanum aviculare has the common names of kangaroo apple or poroporo. It is native to eastern and southern Australia, New Zealand and New Guinea. It is a quick-growing evergreen with dark stems and very dark green leaves. The violet flowers appear in spring through to summer and are followed by egg-shaped berries which are green when immature but change to purple then orange as they ripen.
Similar to Solanum aviculare is S.laciniatum, also known as the large kangaroo apple or large poroporo. It is found in south-eastern and New Zealand. It has very dark green leaves which may be lanceolate or deeply lobed. Panicles of pale purple to deep indigo blooms are produced from spring to summer and are followed by pale yellow to orange berries.
The Solanum is variable in its features. Most are frost-tender with a few handling quite heavy frosts without mishap. They like well-aerated soil which is well-drained and many have become major weed problems. Most prefer full sun or partial shade. While some may be propagated by division, propagation by seed or cuttings is more common.