Mushroom Biology: The Structure and Function of Mushrooms

Let's clear up a common misconception — mushrooms are NOT plants.

Mushrooms are a type of fungus. There are many different kinds of fungi, including molds and crusts. Fungi are distinct from plants because they do not possess chlorophyll, the green pigment that allows plants to manufacture sugar from the sun's energy. They need to absorb their food from the environment in which they live.

Only about 3% of known mushroom varieties are poisonous, and the symptoms of poisoning can vary from gastrointestinal discomfort to death, depending on the type of toxin ingested.

How Do Fungi Obtain Food?

Fungi use fibers called hyphae, referred to as mycelium, to take in food. The mycelium can remain dormant under the ground for many seasons, similar to the roots of plants. Each hypha that is sent out makes its way through earth, wood and plant matter until it reaches the surface.

During the organism's specific growing season, the hyphae develop into mature structures capable of reproducing spores. The structure that you normally see above the ground is the part of the mushroom that is producing and dispersing spores.

Each spore is a single cell that is capable of sending out a hypha that will develop into a group and form its own mycelium. If the hypha of one spore meets up with the hypha of another, it begins the sexual process of spore production through special spore-producing cells.

How Are Spores Produced?

There are two types of spore-producing cells: asci and basidia. In asci, the spores are fully contained within an outer covering. When the spores mature, the tip of the ascus breaks open and the spores are released. In basidia, the spores are produced externally. The spores are released when they break off.

The Mushroom Life Cycle

The spore of a mushroom contains all of the necessary materials to form a new fungus. When the spores of a mushroom are released, they may travel a certain distance before they land. The single cell then sends out hyphae to help establish the fungus and gather food.

After the spore has sent out its hyphae, they will eventually meet up with the hyphae of another mushroom. After the sexual process of reproduction has begun, the mushroom forms the structures of a "fruiting body" that will eventually produce and disperse spores. The egg/button stage is the early form of this fruiting body.

The mature fruiting body can have various structures. The fruiting body may contain a cap, stalk, ring, volva, and gills. The cap normally houses the spore producing surface of the fruiting body.

Types of Mushrooms

Cup Fungi: The spore-producing asci are located on the inner surface of the mature fruiting body. Spores are released in a cloud when the asci break open.

Gilled Mushrooms: Gilled mushrooms have basidia located on the gills on the underside of the cap. The spores are dropped from the gills when mature.

Boletes Mushrooms The basidia are located in tubes within the flesh of the cap of the mushroom.

The spores are released through pores in the surface of the underside of the cap.

Puffball Mushrooms: The basidia in puffballs are contained entirely within the body of the mushroom. A cloud of spores is released when the outer covering collapses or explodes.

When Wild Mushrooms Are Dangerous

Only about 3% of known mushroom varieties are poisonous, and the symptoms of poisoning can vary from gastrointestinal discomfort to liver failure and death, depending on the type of toxin ingested.

Acute liver failure from mushroom poisoning is relatively less common, but it does happen. And in the majority of cases, it’s because an amateur mushroom hunter or backyard forager misidentified a mushroom.

The most common dangerous mushrooms are those belonging to the Amanita genus, especially Amanita phalloides, aptly called “death cap” mushrooms. They contain toxic compounds called amatoxins that damage liver cells.

In less poisonous varieties, digestive symptoms of mushroom poisoning develop as early as 20 minutes to four hours after ingestion and normally pass after the irritant is expelled.

Common Edible Mushrooms In Wisconsin

Morel Mushroom

Oyster Mushroom

Chanterelle Mushroom

Further Information About Mushrooms and Fungi:

 Soil Biology and The Food Web
 Soil Health and Micro-organisms
 The Wood Wide Web-How Fungi Shapes Our Forests
 How To Help Beneficial Fungi
 Fungi Quiz: Test Your Knowldege