The Senna genus is not exclusive to Australia but there is more than 40 endemic species and sub-species. These species were previously included in the Cassia genus and most people would know the plants by this generic name. Unfortunately a number of the exotic Senna species have been identified as serious weeds here.

The plants in the genus range from prostrate plants to small trees but they are typically small to medium shrubs with fern-like pinnate foliage and bright yellow flowers. The flowers are followed by large seed pods. The seeds need treatment with boiling water before planting but will then germinate relatively easily.

The best known of the Australian cassias is Senna artemisiodes (Silver Cassia). It occurs naturally in the dry inland areas of Australia. The foliage is finely pinnate with a silvery appearance and clusters of bright yellow flowers appear at various intervals throughout the year. This shrub tolerates wind, drought and salt-spray and temperatures to -5 C. It requires a position in full sun and good drainage. Pruning after flowering will keep the shrub compact and attractive. There are many subspecies of this genus and they vary quite amazingly. If you have a look at the Australian National Botanic gardens list of species http://www.anbg.gov.au/photo/apii/genus/Senna (Note: some of the spelling on this list is incorrect.) and compare them you will notice the variation. Senna artemisioides ssp. helmsii is particularly attractive.