Types of Fungi: Mushrooms, Toadstools, Molds, and More

Fungi exist all over the world and are as important to our lives as wheat, cattle, fish, or any other living thing. Here are just a few of the reasons to admire this life form.

What's So Special About Fungi?

• Without the various types of fungi on Earth, we would soon be knee-deep in dead leaves and other plant matter that would refuse to rot.
• Trees that died would continue to lie where they fell. Only fungi can break down lignin, the tough material at the heart of woody tissue.
• Our crops would fail because the nutrients that fungi recycle from dead plant tissue would no longer be available.
• Important farm animals like sheep would be unable to digest grass without the help they get from some friendly fungi.

And then there is the sheer beauty of many of these organisms. What would our woods and fields be like without all those stunning mushrooms and (sometimes sinister) toadstools in the fall? This page takes a look at a very important group of living things that, on the whole, we should all be grateful for.

What Exactly Are Fungi?

Scientists used to place fungi in the plant kingdom, primarily because they were thought to be incapable of moving under their own power. Closer study has shown, however, that at least some fungi have reproductive stages involving gametes that can swim.

The most obvious way in which fungi differ from plants, though, is that they do not make food from sunlight and carbon dioxide. Like animals, fungi feed by digesting and absorbing what they need from their environment. Nowadays, fungi are given their own kingdom.

Within the Kingdom Fungi , these are the most important families, or "phyla."

• Basidiomycota: This family includes mushrooms and toadstools.
• Ascomycota: Sometimes called sac fungi, members of this family often have vivid, eyecatching fruiting bodies. This group includes the very tasty morels (see below) and truffles. It also includes the penicillin species which gave us the first effective antibiotic.
• Neocallimastigomycota: These fungi live in the digestive tracts of plant-eating animals like sheep. The enzymes that they produce break down polysaccharides like cellulose, the tough material that gives plants their strength. Once these fungi do their work, the simpler carbohydrates that are produced can be used by sheep as food.
• Blastocladiomycota: This family consists mostly of soil dwellers that digest detritus of all kinds
• Glomeromycota: This is a very specialized family of fungi that live in a beneficial symbiosis with liverworts (small plants similar to mosses).
• Chytridiomycota: These ancient fungi digest tough proteins like keratin (common in skin and hair) and chitin (especially common in the exoskeletons of insects).
• Microsporidia: This is a small group of single-celled, parasitic fungi that mostly infect beetles.

Below, I've included a closer look at the two most important groups, or phyla: Basidiomycota and Ascomycota.

Phylum Basidiomycota

Basidiomycota is a large family and the one we are most familiar with. It includes:

• Mushrooms
• Puffballs
• Stinkhorns
• Bracket fungi
• Jelly fungi
• Boletes
• Smuts
• Bunts
• Rusts
• Chanterelles
• Earth stars

Mushrooms are one of the most noticeable groups of fungi. Most of each fungus organism is hidden from view in soil, leaves, or deadwood (depending on the species). The large fruiting bodies that emerge (mostly in the fall) are conspicuous and often very beautiful. Some mushrooms are even bio-luminescent, as you can see in the video below.

How Do They Eat?

Like most fungi, Basidiomycota are saprotrophic, which means they decompose dead matter, including the toughest plant materials like lignin—a major structural component of trees.

Underground, Basidiomycota produce large networks of tiny tubes called "hyphae." These grow through dead plant and animal material by secreting enzymes that dissolve a pathway. The dissolved material is absorbed and digested as food.

How Do They Reproduce?

The fruiting bodies we see above ground disperse spores, which develop into new individuals. Some of these fruiting bodies, like the Russulas pictured above, make very good meals. Others, like the Amanitas pictured second, will make you very sick. Exercise caution!

Phylum Ascomycota

Ascomycota is the largest phylum of fungi with over 64,000 species. Some of these fungi are extremely valuable to humans for their culinary applications. There are two main groups, or subphyla: Pezizomycotina and Saccharomycotina.

Subphylum Pezizomycotina

Pezizomycotina fungi have fruiting bodies similar to mushrooms and include morels, truffles, ergot, and cup fungi. Truffles (Tuber genus) are one of the most expensive foods on the planet. It is impossible to grow truffles on a large scale, and they are very rare even in their favorite woodland habitats.

Pigs or dogs with especially sensitive noses are used to locate the highly prized underground fruiting bodies. White truffles sometimes cost around $5 per gram ($2,000 per pound), but their value changes each season depending on supply.

Subphylum Saccharomycotina

This group comprises most of the yeasts, including the very important baker's yeast. The white bloom on grapes (pictured above, third) is a mixture of wild yeasts and molds. In the past, natural yeasts present on grapes were relied on to ferment the juice and produce wine.

Nowadays, commercial winemakers usually innoculate grape juice with a high dose of a single variety of specially grown yeast like Saccharomyces cerevisiae rather than relying on the slower-growing wild yeasts. Whichever yeasts are used, the process is essentially the same. The yeasts consume sugar (without needing oxygen) and produce alcohol and carbon dioxide in the fermentation process.

Harmful Fungi

Most fungi are beneficial. Certain mushrooms make wonderful ingredients as-is, and yeasts help us create some of our staple foods like bread. Detritus-eating fungi keep our crops supplied with nutrients via their efficient recycling of decaying organic material. There are, however, some fungi that can be harmful to humans.

• Athlete's foot is caused by the Trichophyton fungus.
• The spores from some Ascomycota, like the powdery mildews, are a serious problem for gardeners and farmers, especially during wet years.
• Late potato blight is caused by Phytophthora infestans, which is not a true fungus but is very closely related. It and other water-molds turn plant tissues to mush. In the 19th Century, most of the human population in Ireland relied on potatoes for food. Potato blight wiped out crops and millions of people died or were forced to emigrate.
• Fungi, especially molds, can affect prepared foods like bread, fruit preserves, pickles, and cheese. If mold has penetrated deeply into food, it needs to be discarded.
• Ergot is an interesting fungus that can thrive in stored cereals like rye if they become damp. The hallucinations and convulsions caused by Ergot ingestion were responsible for "Saint Anthony's fire" during the Middle Ages. Whole communities were seized with strange symptoms that were often ascribed to witchcraft.
• Dutch elm disease has been responsible for the deaths of millions of elm trees around the world. Beetles that bore under the bark of elm trees carry a fungus that invades the trees' inner tissues.
• A few species of parasitic fungi affect farmed and wild fish.

Wood-Decay Fungi

The types of fungi that cause wood decay are crucial in recycling nutrients from fallen trees but can be a menace in wooden homes and other buildings. Usually, the complete decay of dead wood involves many kinds of fungi. Wood decay fungi are usually broken into three groups:

• Brown-rot fungi: produce hydrogen peroxide which attacks cellulose
• Soft-rot fungi: produce an enzyme called cellulase which digests cellulose
• White-rot fungi: produce enzymes capable of digesting lignin

Despite the damage that fungi can do to homes and foods, I stand by my original statement. Fungi, overall, are good for us, and we should be grateful for them!

Some of these are beautiful, and others are a little sinister. A number of these fungi are edible, but you should never eat any fungi from the wild without expert advice. Many people die each year as a result of eating poisonous species.