Glacier National Park probably harbors more than a thousand species of fungi. The most visible ones are the mushrooms. They range from edible morels (usually growing in newly-burned areas), chanterelles, boletes, shaggy manes and lactarius to lethal deathcaps and the fly amanitas. Some have medicinal properties like the emetic russula. They range in shape from puffballs and coral fungi to bird nests and earthstars. Fungi grow on decaying wood and living trees. Some are host-specific, like the horse's hoof fungus which grows on birch trees or the honey-brown winter mushroom found on aspens.
While in Glacier, remember that it is illegal to collect materials, including plants and mushrooms, in a national park. If collecting mushrooms outside a park, remember that one mistake in identification can be fatal. Considering the thousands of species, and the many nuances of proper identification, it is necessary to be absolutely sure.
Mushrooms represent the fruiting body of fungi, but most of the organism is underground (or inside host trees) as tiny rootlets or mycelia. As beautiful and brightly-colored as mushrooms are, the real action is below the surface. Fungal mycelia accomplish most of the decay of living things in forests this far north. It is too cold for much bacterial action. Were it not for the fungi, recycling of dead material back to soil would be severely diminished. Fungi are classified in a kingdom that is separate from plants, animals, and bacteria. They appear similar to plants in that they often grow from soil, but are structurally and reproductively very different. They cannot produce their own food through photosysnthesis, so they consume dead material and sometimes parasitize living things. It is vital work.
The mycelia also form thick webs over the roots of seed plants (mycorrhizae) and assist the roots to gather nutrients and water. Most conifer trees--pines, spruces, cedars, hemlocks, firs--could not live without fungi. In the ancient forest of the McDonald Valley, the amount of fungi rootlets in the soil likely approaches two tons per acre!