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)

Peas like acacias are legumes, possessing root nodules containing the N-fixing bacterium Rhizobium (members of the genus Alnus, alders, are the only non-legumes to form this association). Members of the Fabaceae are common in the understoreys of open-forests, woodlands and shrublands. Most produce heat-resistant seeds, which are stored in the soil and may germinate prolifically after fire.