Plants, Nutrients and Australian Soils

Groups of Australian plants that possess N-fixing symbionts include:

• Wattles (Acacia)
• Peas (e.g. Sturt's desert pea)
• She-oaks (Allocasuarina and Casuarina)
• Cycads (e.g. Macrozamia and Cycas)

Although casuarinas also develop root nodules, they have a different root symbiont. Frankia, an actinomycete, forms associations within the Casuarinaceae and 7 other angiosperm families. Like the peas and acacias, casuarinas are common in the Australian landscape, especially in dry country and on infertile soils. They are also generally well adapted to recover rapidly after fire either from seed or via vegetative regrowth.