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NatureSpeak Articles

Are mushrooms fungi?

Cauliflower mushroom Sparassis crispa (Photo: Sharmin Gamiet)

Yes, of course mushrooms are fungi, but not all fungi are mushrooms. We are familiar with fungi that produce relatively large, showy reproductive structures such as mushrooms, truffles, puffballs, shelf, and cup fungi, but in reality they are less than 1 percent of the described species. The majority of fungus produce reproductive structures not visible to the unaided eye and include yeast in bread, fermentors in wine, and sources of antibiotics. Here are some other fun fungal facts.

The most familiar kind of mushroom has a cap with gills (radiating blades) on its underside. Millions of microscopic reproductive units called spores are discharged from the gills and dispersed by air currents. Only a small percentage of spores land in a favourable environment, where they germinate to form new fungi.

Although fungi have been traditionally grouped with plants, they have no direct evolutionary connection. Fungi are as distinct from plants as they are from animals or insects, although they share similarities with each. Unlike plants, fungi lack chlorophyll and therefore are unable to manufacture their own food from sunlight. Like animals and insects, they must feed themselves by absorbing carbon compounds from the immediate environment. Fungi have evolved enzymes for digesting substrates such as chitin (insect exoskeletons), keratin (hair, skin, horn, feathers), cellulose (most plant material), and even lignin (wood).

How else are fungi like insects and plants? The part of the mushroom fungus that digests nutrients is an intricate web of fine threads collectively called the mycelium (plural: mycelia). Individually they are called hyphae and their walls that extend through the soil or aggregate to form a mushroom or other type of sporocarp (fruiting bodies that produce spores) are mainly composed of chitin and cellulose. Chitin is part of the exoskeletons of insects but is found nowhere in the plant kingdom. Cellulose occurs in wood and most plant material.

Mushrooms, or more exactly the fungi that produce them, are vital part of our environment. Despite some having a bad name, the overwhelming majority are beneficial. A few are parasitic, feeding on living organisms, usually trees. The rest are either saprophytic or mycorrhizal. Saprophytic fungi are nature’s recyclers. They replenish the soil by breaking down complex organic matter (wood, dung, humus, etc.) into simpler, reusable compounds. Mycorrhizal fungi form a mutually beneficial relationship with the rootlets of plants in which nutrients are exchanged. They are critical to the health of our forests, as many trees will not grow without them.

The fall is the ideal time to develop a passion for local fungi. Although we do have some mushrooms that make an appearance in the spring, the real show begins as the nights become cool and moist and the autumn rains begin to fall. The Whistler Naturalist Society is putting on a two-day event in October to celebrate everything weird, wild and wonderful about mushrooms!

Written by: Kristina Swerhun

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