Solanum.
Family Solanaceae > Subfamily Solanoideae > Tribe Solaneae.
Solanum species are found almost worldwide but the majority are from Central and
South America with some from Africa and Australia.
The division of the genus into subgenera etc. is not settled.
Many species are variable in appearance and some are so similar they
can be referred to as species complexes.
The estimated number of species varies from 1000 to 2000 but may be around 1400.
Australia has up to 100 native species and a number of introduced ones.
They have many uses including food (tomatoes and potatoes), ornamentals (S. wendlandii),
and medicines. Some are toxic to humans and many are weeds.
They can be annuals or perennials, herbs, shrubs, climbers or small trees.
Stems are occasionally smooth but usually have simple, stellate or glandular hairs.
There may be straight or curved prickles.
Leaves are alternately arranged but may sometimes appear to be opposite.
There is usually a petiole but sometimes there is none.
The blades are simple to deeply lobed and there may be pseudostipules and prickles.
Inflorescences are terminal but growth of a side branch can make them appear leaf opposed or extra-axillary.
Usually small and bisexual, the flowers are mostly in clusters of various types.
Inflorescences may or may not be on stalks and bracts can be present or absent.
Individual flowers can be on smooth or hairy pedicels or directly attached.
Flowers are mostly radially symmetric.
The cup, star or bell-shaped calyx has 5 (4 – 10) lobes on a calyx tube.
It may continue to grow in the fruit.
The corolla consists of a short tube with 5 (4 – 10) lobes in a star-like pattern.
Colours include blue and purple plus white and rarely yellow.
There are often hairs on the outer surface of the lobes.
The 5 stamens insert into the corolla tube at various levels.
The short, smooth or hairy filaments hold the anthers above the corolla.
The tips of the anthers commonly form a tight ring around the style.
The basifixed anthers almost always open by terminal pores that may develop into short slits.
There may be a small disc around the base of the ovary.
The ovary, of 2 fused carpels, can have up to 4 locules due to false septa.
The locules have numerous ovules with axile placentation.
The single style holds the capitate or bifid stigma among or above the anthers.
It can be smooth or hairy and may be bent.
The fruit are smooth berries that are mostly spherical and fleshy.
They ripen from green to red, yellow, purple, black or white.
The seeds are flattened and roughly spherical to kidney-shaped.
J.F.
