David Noble is a member of the Sydney Fungal Studies Group (not to be confused with Mr. Wollemi-Pine-David-Noble).
David has a background as a science teacher and once worked at the NSW Herbarium. He played a key role in the discovery of Leptospermum spectabile. With his inexhaustible knowledge of fungi, David introduced us to many fascinating species.
Historically, discussions about nature have focused on flora and fauna. However, we are now encouraged to consider the “three Fs”—flora, fauna, and fungi. Fungus belong to their own kingdom and are more closely related to animals than plants. Despite their importance, fungi are rarely protected by environmental legislation.
Fungi are ubiquitous, found in plant roots, soil, leaves, animal stomachs and digestive systems, and even underwater. They are estimated to make up 25% of the world’s biomass. One extraordinary example is the Honey Fungus in Oregon, often described as the largest organism on Earth. It spans approximately five square kilometers and may weigh up to 35,000 tons. Remarkably, a single teaspoon of soil can contain hundreds of fungal species.
Fungi are eukaryotes, meaning their cells have a nucleus. They come in a wide array of groups, including Basidiomycota (mushrooms), Ascomycota (sac fungi), yeasts, Chytridiomycota, and Zygomycetes, among others. Typically, fungi consist of hyphae—long, cylindrical cells that form living threads. Hyphae grow within a substrate and can stretch for many meters, often at a microscopic scale. Networks of hyphae are called mycelium. These hyphae secrete enzymes that break down plant or other organic material, absorbing the resulting nutrients.
When conditions are favorable, mycelium produces spore-bearing structures such as mushrooms, which are often visible. Spores, released from gills or pores, enable reproduction. Fungi can reproduce asexually through hyphal division or sexually via spores. These spores, typically 3 to 30 micrometers in size, are wind-dispersed and nutrient-free. Interestingly, spores may enhance rainfall by concentrating moisture in the air.
Fungi cells, like plant cells, have a cell wall, making them particularly hardy. However, unlike plant cell walls, fungal cell walls are composed of chitin and complex polysaccharides. Some fungi, like yeasts, are unicellular, while others, like mushrooms, are multicellular. Hyphae can grow in light or darkness, usually requiring water and oxygen to thrive. Fungi colonize various substrates, including wood, soil, dung, food, and plant material.
It is believed there are about 1.5 million fungal species, yet only 150,000 have been formally described.
Fungi are essential decomposers in ecosystems, breaking down complex organic matter into simple molecules. Many species are classified as mycorrhizal fungi, forming symbiotic relationships with tree roots. In this mutualism, fungi provide water and nutrients to trees in exchange for sugar-based materials. There is growing excitement about the idea that forest root-fungi systems may function as a vast network, not only exchanging nutrients and water but possibly transmitting electrical signals and communication. However, David advises caution with these claims—though it is clear fungi can move materials within these networks. Remarkably, 80-90% of plant species form mutualisms with mycorrhizal fungi.
Interestingly, the Proteaceae family does not rely on mycorrhizal fungi. Instead, they have proteoid roots to obtain nutrients. In a related note, Proteaceae flowers in South Africa house a non-harmful fungus that is cultivated by mites.
Orchid seeds generally lack endosperm, meaning they have no nutrient reserves to initiate germination. Instead, the seed must come into contact with a fungus to germinate. For example, Caladenia orchids form a close bond with the Serendipita fungus.
The diversity of fungi in old-growth forests is astonishing, with many species acting as vital wood decomposers.
David introduced us to a fascinating variety of fungi, including the Flame Fungus, which produces striking, erect, bright-orange finger-like growths. He also discussed lichens, unique organisms that break down rock into soil. Lichens are a partnership between two fungi and an alga, demonstrating the remarkable adaptability of fungi in nature.
We also briefly examined Thismia megalongensis, a plant that strongly resembles a fungus and could easily be mistaken for one.
Some fungi have a significant negative impact on both nature and humans. For instance:
- Dutch Elm Disease, caused by the fungus Ophiostoma, has devastated elm trees.
- Myrtle Rust, a type of rust fungus, has wreaked havoc on various plant species and causes serious issues in wheat crops.
- Phytophthora, though often mistaken for a fungus, is actually a water mold that causes widespread damage.
Fungi also pose medical risks to humans, potentially causing conditions like pneumonia, skin infections, and meningitis, which can sometimes be fatal.
Fungal infections impact wildlife as well. For example:
- Certain fungi kill bees and bats, threatening their populations.
- The chytrid fungus group has led to catastrophic declines in amphibian populations worldwide.
Fungal spores are easily dispersed, enabling them to colonize new locations rapidly. Some fungi, such as smuts and rusts, are infamous for their destructive effects.
One particularly notable example is ergot, a fungal infection of rye. Eating rye bread contaminated with ergot can lead to ergotism, which causes severe muscle spasms and can even be fatal. In some cases, ergot produces compounds similar to LSD, leading to intense hallucinations in those who consume it.
However, fungi are also incredibly useful to us. They play key roles in food production, baking, brewing, winemaking, cheesemaking, and fermentation. Fungi are used to produce antibiotics, such as the famous Penicillium (used to make penicillin), and even insecticides.
Some fungi, such as Cordyceps, grow on insects and other animals, manipulating their behavior to further the fungus’s lifecycle—earning them the chilling nickname “Zombie Fungi.”
Yeasts and truffles belong to the Ascomycetes, a group capable of breaking down cellulose. Mushrooms are part of the Basidiomycetes, which often decompose wood by releasing powerful enzymes.
During our exploration, we encountered waxcaps, which display a range of vibrant colors and can parasitize plants. We also saw coral fungi with coral-like structures close to the ground, Earthstars with their characteristic puffball centers releasing dust-like spores, and Bird’s Nest Fungi, which resemble miniature nests.
Stinkhorns, another fascinating group, are commonly found in mulch. Their bright red fruiting bodies produce a foul-smelling, slimy substance that mimics rotting meat. This odor attracts flies, which then disperse the spores.
Slime molds, found in the Myxomycota group, can form large colonies in natural and urban environments.
Australia is estimated to have around 250,000 fungal species, yet only about 15,000 have been formally described. Identifying whether fungi are native, introduced, or cosmopolitan is a challenging task. Interestingly, some native Australian fungi have been introduced to other parts of the world, much like Australian plants. Unfortunately, the number of paid mycologists is dwindling.
Fungi often appear seasonally, with their peak activity from March to July. If a significant rainfall—about 80 mm or more—occurs in January, it can trigger a robust fungal season, especially if followed by additional rains. In 2024, for example, I observed a bumper season, with many people stopping in Penrose State Forest to harvest Saffron Milk Caps (my wife even collected some from a radiata pine forest).
One fungal community, the Hygrocybe Community of Lane Cove National Park, is officially recognized and protected under legislation as an endangered ecological community. In some bushland areas, experts like David are now required to survey the land to determine if this particular community is present. Interestingly, fruiting bodies of these fungi can sometimes exhibit “rosecomb” deformities, which are believed to be caused by chemical pollutants.
David showcased a stunning array of close-up photos, highlighting the incredible beauty and diversity of fungi.
To identify fungi properly, it’s essential to photograph the sporocarps, including details of the gills or pores, while also documenting the location, habitat, and substrate.
The presence, prevalence, and diversity of fungi remind us that they represent an entire kingdom of life we are only beginning to understand. When a tree or patch of bushland is destroyed, countless fungal species may be lost along with it. The loss of old-growth forests likely results in the destruction of intricate fungal networks, which are critical to the ecosystem.
We must continue to study, protect, and conserve these organisms. David’s expertise and insights into the world of fungi provided a truly valuable and enlightening talk.
(Check out David’s blog: David Noble’s Blog)
Recent Fungi in the News
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ABC News: Read about the fascinating work being done at the National Herbarium of Victoria and the Royal Botanic Gardens to document fungi biodiversity. Click here to learn more.
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From Tasmania: “Follow the Rain”—a documentary exploring fungi and its role in Tasmanian ecosystems—is now available on Netflix. There’s also talk of an upcoming IMAX version!