What Are Mushrooms?
The types of fungi that produce mushrooms are a subset of the Fungal Kingdom, a large grouping of organisms that share similar traits. The Fungal Kingdom not only includes the species that produce the 3-dimensional objects that we can touch and easily interact with (i.e. mushrooms), but also other microorganisms such as yeasts and molds. The Kingdom Fungi is differentiated from plants, animals, protists and bacteria by the facts that fungi are comprised of cells that 1) are eukaryotic, 2) have cell walls that contain chitin, 3) must get their food externally, and 4) expel carbon dioxide through respiration.
On the taxonomic tree of life, fungi are closer related to the animal kingdom than the plant kingdom. This makes sense from a biological and physiological standpoint when one learns the details of how fungi grow and survive. But on a more subjective level, fungi almost seem like animals themselves. Fungi are acutely aware of their environments and rapidly adapt to changes in it. When cultivating fungi, one gets the sense that they are caring for a pet or small child considering the care and attention required to keep the fungus alive. And when studying the dynamics and complexity of fungal symbiosis and metabolite production, one almost gets a sense of an innate intelligence or sentience in the fungus that is not easily explained by simple chemistry and biology alone.
The fungal kingdom is broken down into several sub-groups, or phylum, based on differences in spore production strategy. The main phyla in the fungal kingdom include:
- Chytridiomycota – Aquatic fungi that number approximately 700 species, in 105 genera.
- Glomeromycota – Obligate, generalist mycorrhizal fungi that number approximate 160 species, all of which form mutualistic symbiotic relationships with 80-90% of all plants on the earth.
- Zygomycota – A diverse group that includes some common fermenting fungi and molds and numbers approximately 1,000 species.
- Ascomycota – Fungi that develop spores in balloon-like sacs and number approximately 64,000 species. This group includes beneficial molds, such as Penicillium species, as well edible mushrooms, such as the Morels.
- Basidiomycota – Fungi that develop spores on club-like structures and number approximately 31,515 species in 1,589 genera. This group includes most of the familiar wild-harvested and commercially cultivated fungi.
While all these fungi play interesting and important roles in nature, it is the last two groups that produce the delicious, medicinal, and remediative mushrooms many people are familiar with. However, what we commonly called “mushrooms” are just a small piece of a much larger body of tissue that produces them. This larger body is a densely woven network known as mycelium. As explained in our page on The Mushroom Lifecycle, this mycelial mass is formed when two spores released by parent mushrooms grow together and branch through their environment in search of food and water. Much like the apple on a tree, the mushroom is the reproductive strategy of the fungus, while the mycelium (like the tree) is the vegetative stage of the mushroom lifecycle.