The mention of fungi often invokes visions of rusts, blights and rots.
Dr Trevor Crosby looks at the fungi you might find in your garden
To many gardeners, these mean ruination of prized plants and crops, as well as the spoiling of hard-earned produce.
However, there are many beneficial fungi, such as those forming mycorrhizal associations, that lead to the success of land plants. Then there are all those fungi that live on dead plant material (saprophytes) and break it down so it becomes available to other life forms.
In return, many organisms are dependent upon fungi as food.
Much of the time, the fungal networks of fine hyphae are invisible to us. It is only when their reproductive stages appear – in the form of mushrooms – that their diversity of shape, form and colour becomes apparent to the gardener’s naked eye.
In New Zealand, there are some 8400 species of fungi recognised, but it is estimated that the true number is more likely to be around 23,000 species.
The multilayered food forest at the Sanctuary Mahi Whenua, at the Mt Albert campus of Unitec Institute of Technology, was started in 1999 and is now part of a sustainable ecosystem. Original nursery trees have been felled and, together with pruned branches from retained trees, left in the food forest to decompose naturally. Now a range of decomposing fungi is appearing.
The southern cinnabar polypore fungus, Pycnoporus coccineus, is a bright orange-red bracket fungus.
It can measure 10cm x 8cm in size and over time, the intensity of the colour fades.
Found in both Australia and New Zealand, it is a white-rot decomposer of wood, and produces powerful lignolytic enzymes (laccases) to break down lignin and tough polysaccharides in the wood in a way that few other organisms can do as well. This makes it an important species in the breakdown of wood as it makes the byproducts of the process available for use by other organisms.
The laccase enzymes have also shown potential to be used in biotechnology processes.
The turkey tail fungus Trametes
versicolor has striking concentric zones of brown and tan on the upper surface.
Its undersurface is white. Over time, green algae can grow over the upper surface, making this fungus less obvious. This worldwide species is 8cm × 5cm and the leathery-textured flesh is about 1-3mm thick.
Turkey tail is recognised as a medicinal mushroom in Chinese medicine (yun zhi) and in Japan.
In the food forest, turkey tail fungi have been found mainly on stumps and large branches of the nursery poplar trees that were felled about two years ago.
The native edible wood ear fungus,
Auricularia cornea, is a common wood-decaying fungus.
It measures 15cm × 8cm in size and can be found at all times of the year.
Its flavour is generally regarded as insipid and is noted more for its texture, especially in Chinese cuisine: it has been described as a bit like tender bacon rind. Maori knew this fungus as hakeka, and it is said that they only ate it when better food was in short supply.
In the late 19th century, large quantities were collected and dried for export to China, especially from Taranaki where it became known as “Taranaki wool”.
And finally, if you’re going, “Wow amazing? Is it real? A spaceship! What flower is that?”
Worry not. You are only feeling the sense of unreality that is common in first encounters with the earthstar fungus. This 5-7cm wide inedible mushroom, Geastrum tenuipes, is native to New Zealand though it is uncommon. It lives in and breaks down leaf litter.
This fungus looks like a puffball fungus when it first breaks the surface. Then the outer layer of tissue splits open to give pointed rays of a star that bend and elevate the inner 2cm diameter spore case from its immediate surroundings.
Drops of water falling onto the flexible, thin-skinned spore case generate a sufficient pressure change within the spore case to force a puff of spores through the small opening on top.
The soft tissue of the pointed rays soon disappears, presumably through being eaten by a range of invertebrates.
So next time you bemoan the effects of unwanted fungi on your plants or produce, remember that these fungal species are quietly doing what they do best – ensuring locked-up nutrients in dead plant material are released for use by other organisms in your garden.
Southern cinnabar polypore fungus, Pycnoporus coccineus.
Earthstar fungus, Geastrum tenuipes.
Wood ear fungus, Auricularia cornea.