There are many species of Indigofera worldwide and some of these have been used as a source of the blue dye indigo over the centuries. There are around 30 species that are native to Australia, but very few are known to cultivation. Of the 30 species, 28 occur in West Australia, though not necessarily exclusively.

By far the best known species is Indigofera australis, commonly called Austral Indigo. It is native to all states of Australia. This is a beautiful shrub or small tree to 5m, though in cultivation 2m is more usual. The pinnate foliage is particularly attractive with its rounded leaves of an unusual blue-green shade. Sprays of scented mauve pink pea-shaped flowers appear, mainly in spring but also occasionally at other times of the year.

Indigofera australis is best grown in semi-shade where there is ample moisture, though it will tolerate short periods of drought. Like other members of the Fabaceae family, it fixes atmospheric nitrogen. It is easily propagated from seed but steps must be taken to break seed dormancy. Soaking them in boiling water and leaving them overnight is usually sufficient

Apart from its obvious ornamental appeal as a garden specimen, Austral Indigo is also valuable as a food plant for Australian butterflies. Common Grass Yellows and Common Grass Blues use it as a food plant for their larvae, so plant one if you would like to encourage these little jewels to breed in your garden.

Indigofera pratensis (Forest Indigo) is another species occasionally seen in cultivation. It is native to tropical Qld, NT and WA. This is a low-growing plant that rarely exceeds 60 cm tall. The foliage is hairy and the flowers are purple. You can see a picture at
http://farrer.riv.csu.edu.au/ASGAP/jpg/i-prat.jpg
Other species such as I. leucotricho, I. helmsii, I. baileyi have been declared endangered species in their natural habitats.

Illustrations from top to bottom:
1. & 2. The pea-shaped flowers and buds of Indigofera australis.
3. The handsome blue-green foliage of Indigofera australis.