Fungi and Australian Flora

The following is taken, and in places paraphrased, from Native Australian Plants: Horticulture and Uses. by Krystyna Johnson & Margaret Burchett. University of New South Wales. 1996. Please refer to this book for a more complete treatment.

mycorrhiza - a symbiotic association of plant roots and fungi, the fungi deriving nutrition from the plant, the plant deriving enhanced mineral uptake via fungal absorption from the surrounding soil. Often seen in Australia as an adaptation by plants to very low mineral levels in the soils. Ectomycorrhiza are those in which the fungus surrounds the root to form a mantle and hyphae penetrate between outer cells of the root to form the net. Endomycorrhiza are those in which the fungal hyphae enter the root cells, forming structures such as the arbuscules and vesicles.

As with other seed plants, apart from the absorption of tiny amounts of nutrients by leaves (for example, boron from rain in coastal areas, sulfur from polluted air near smelters), the fine feeder-root system is the key site of nutrient uptake. In eucalypt forests it is usual for most of the feeder-root system in the litter and down to 30 cm in the mineral soil to have mycorrhizas - that is, symbiotic associations with fungi. These fungi can promote tree growth through enhanced uptake and transfer of limiting nutrients such as phosphorous and nitrogen. They can also enable some species of eucalypt to grow on calcerous soils where soil pH conditions normally make it very difficult for the plant to obtain micro-nutrients such as iron.

In Australia, many thousands of species of higher fungi form ectomycorrhizas with eucalypts. The fungus obtains its carbon from the plant: sucrose is converted to glucose by cell-wall bound invertases. The fungal partners produce conspicuous sexual fruiting bodies such as mushroom-like fruit and puffballs. Truffle-like fungi are very abundant in eucalypt forests and may form tripartite relationships with tree roots and foraging marsupials. The marsupials obtain nourishment from the fruiting bodies and distribute spores through their faeces.