Mushrooms and Other Fungi

A clump of mushrooms growing out of moss and covered in snow.
Lyophyllum descastes, or the fried chicken mushroom, blanketed by an early snow.

NPS/B. Garcia Photo

What are fungi?

Fungi are a large group of eukaryotic organisms that includes molds, yeasts, mildews, rusts, smuts, and mushrooms. They produce spores and are unable to photosynthesize. Fungi are not plants—in fact, they are more closely related to humans! They may often go unnoticed, but many species play important roles in shaping our environments, advancing modern medicine, contributing to our diets, and affecting our health. Many scientists estimate the total number of species of fungi to be in the millions, though only approximately 140,000 have been described.


What are mushrooms?

Mushrooms are the reproductive structures of certain types of fungi. The bulk of the organism often grows underground or in wood. It is composed of root-like threads called hyphae, which cumulatively form vast networks we refer to as mycelium. Mycelial networks produce mushrooms to help form and distribute their spores (seed-like cells) through which the fungus can reproduce. Think of the mushroom as an apple and the mycelial network as the tree!

Well over 14,000 species of mushroom-producing fungi have been described, and that is likely only a fraction of the species that exist. Mushroom-producing fungi make up a very small group within the fungal kingdom, but, due to their size, they tend to be the most visible to us. Some wild mushrooms look structurally similar to the white button mushrooms available in many grocery stores, with a stem and a cap with gills underneath; others can have a sponge-like surface beneath the cap, or even spines. Some don’t even have caps and look like they’d be more at home in a colorful coral reef than in the forest! Some species produce prized edible mushrooms, while others are deadly poisonous. Mushrooms are also sometimes used for making decorations, dyes, fabrics, and holistic medicines.


What do mushrooms do?

Perhaps a better question would be, “What don’t mushrooms do?” Mushroom-producing fungi are highly interactive, often forming relationships with plants, insects, bacteria, and other microbes. They give structure to soil, break down wood and other organic materials, and help make the nutrients from dead plants available to growing plants. Their lifestyles and ecological roles are largely determined by the way each species has evolved to take in nutrients. Mushrooms are heterotrophic, meaning that, unlike plants, they cannot produce their own food.

Follow the links below to learn about three important ecological roles mushrooms play at Mount Rainier: decomposers, parasites, and mycorrhizae. Each section highlights a few interesting species that are commonly found at Mount Rainier National Park. Though most mushroom species will fit fairly comfortably into one of these categories, many species fill multiple ecological roles; parasites can also be decomposers; mycorrhizal fungi can adversely affect their host plants. Fungi tend to elude neat classification and categorization, frustrating and fascinating beginners and seasoned mycologists alike!

When observing mushrooms, pay attention to the context in which they are growing. Are they fruiting on wood, leaf litter, moss, or bare soil? Which trees are nearby? Are there shrubs or bushes in the area? Is the forest open and sunny or shady? These sorts of observations can sometimes help you towards an identification, if that is your goal, but they also help to remind us of how interconnected the natural world is. Species interact with others in dynamic and complex ways. A fungus is not simply an individual, but a part of a multispecies tangle of associations in which trees, fungi, microbes, and others collaboratively live and die.

A brown conk with pale underside growing out of a tree.
Decomposing Fungi

Decomposing fungi get their nutrients by digesting dead or decaying organic matter such as leaves, pine needles, and wood.

Yellow-white mushrooms erupting out of mossy ground.
Mycorrhizal Fungi

Mycorrhizal fungi form complex symbiotic relationships with the roots of trees and other plants.

A clump of wavy-like pale mushrooms.
Parasitic Fungi

Parasitic fungi form relationships with other living organisms, but benefit to the detriment or death of their host.

A collection of small tan mushrooms laying on moss next to a curved knife.
Mushroom Picking

While collecting mushrooms is permitted at Mount Rainier, identifying wild mushrooms can be extremely difficult.

Last updated: April 21, 2021

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