The Mysterious Kingdom of Fungi

Imagine a world where fallen trees are stuck in time, unable to decompose and nourish the soil. Plants are more susceptible to disease and drought. Animals, including humans, struggle for subsistence. Picture a world with no wine, bread, or beer, where many life-saving antibiotics don't exist. That is the world we would live in without fungi. Although they make a big impact on our lives, these spore producing organisms are often invisible to the untrained eye. “There are currently over 100,000 described fungi. And the thing is, we don't know how many more fungi there are in the world," said Laurel Kaminsky, University of Florida librarian and lichen researcher.

"It's not like plants, or animals where they're much easier to find and tend to be more charismatic. With fungi and lichens, you really gotta look for them. We estimate that there's a million plus species, which suggests that we still have to find hundreds of thousands more.” With so much still unknown about fungi, the future of many lineages of the kingdom is uncertain. Climate change, sea level rise, and habitat loss threaten fungal diversity in Florida, and could even lead to the extinction of undiscovered or rare species. “One big problem for fungi is that we have so little information about them relative to how many species there are," said Matthew Smith, a professor in the UF Department of Plant Pathology the curator of UF’s fungal herbarium.

"We really don't have a very good idea of which species are rare and which are common, because there's so much diversity and they’re so poorly documented.” With no existing baseline, it will be difficult to know how fungi populations are impacted as Florida’s environment changes.

The term  “fungus”  (plural: fungi) encompasses a diverse kingdom of species with vastly different shapes, sizes, and life cycles. Fungi have more in common with humans than plants. Just like us, fungi are multicellular eukaryotes and heterotrophs, meaning they contain many cell types forming different kinds of tissues and derive their energy from food that they eat, rather than through photosynthesis. Unlike animals, though, fungi eat by secreting enzymes that digest their food outside of their bodies. Once the nutrients are broken down by the enzymes, the fungi absorb the nutrients for themselves in a process called  absorptive nutrition .

Also, unlike humans, fungi have tough cell walls like plants. However, these cell walls are not made of cellulose—instead, the walls are made up of chitin, similar to the material that makes up bug and crustacean exoskeletons. If all of that isn’t weird enough, fungi have indeterminate growth, meaning they can grow forever in the right conditions.

A common group of fungi you’ve likely heard of are lichens. Lichens are a “sandwich” of fungi and algae that benefit each other in a co-evolved, symbiotic relationship. The algal part of the relationship provides food through photosynthesis, while the fungus provides protection for the algae and facilitates growth of the fungal body. 

It’s clear that they’re unlike any other creature that we can see with the naked eye. So, for many years, scientists pondered the same question: “What are fungi?” 

“Everyone just thought they were weird plants for a long time. And then over time, it became clear that they were not just weird plants, and that they are their own group," said Smith. 

The field of mycology, or the study of fungi, is fairly new. Although the  Swedish biologist Carl Linnaeus  described some species of fungi in the 1700s, few people at the time were mycologists. Historically, the scientists who made progress in the field were doctors, botanists, brewers, and farmers, close observers of nature or people with microscopes. Often, fungi were stumbled upon, rather than intentionally studied. 

Today’s technology has made clear some of the mysteries of the elusive kingdom of fungi and has brought about a new generation of mycologists. 

Molecular biology, or the study of the molecules that make up living things, has allowed mycologists to analyze the DNA and biochemistry of fungi. These scientific advancements have suggested new knowledge about species distribution and how fungi impact their ecosystems.  

“Molecular biology has really changed our ability to study fungi,” said Smith. “It gives us a window into what they are doing in the environment.” 

Without fungi, our world would look very different. The kingdom plays an important role in the function of many ecosystems we rely on.

Mycorrhizal fungi form symbiotic relationships with plants by attaching to their roots. The plant provides food in the form of sugars for the fungus, while the fungus serves as a “bendy straw” for the plant to reach more nutrients and water, allowing both species to survive through stresses like drought and diseases.

Some species of lichens provide additional benefits to the environment transforming nitrogen in the air into a crucial nutrient used by all living things to build the structure of our DNA. And, while we typically think of decay as a bad thing, wood decay fungi consume even the toughest components of dead wood and turn them into soil nutrients.

However, just like any kingdom, there are some bad guys. Pathogenic fungi threaten both plants and animals, creating challenges for environmental and public health. In recent years, a species of yeast named Candida auris received news coverage after being found in hospital and nursing home ventilation systems during the COVID-19 pandemic. While our human immune systems can typically prevent fungal infections from establishing, pathogenic species like C. auris can pose a significant threat to immunocompromised individuals.

Fungi make a distinct impact in our everyday lives. Watch the video below to learn how fungi might be present in yours!

Habitat loss through sea level rise and inland development are similarly threatening to our knowledge of fungi. Fungi are very specific about the environment they live in, since they have evolved to become so specialized. The loss of land in the Everglades, for example, could impact lichen diversity. 

“Fungi are like the wild wild west. There's so much we don't understand. And there's so few people studying,” said Kaminsky. Both Smith and Kaminsky agree that citizen efforts could be critical to the scientific understanding of fungi distributions. They suggest the use of  iNaturalist , a crowd-sourced tool that scientists in many fields use to study species. Users can take photos of fungi in the wild (or in their backyard), upload the location and time of their finding, and receive help from others with the identification of the species.

“Touch them, go find them, see them, take pictures and put them on iNaturalist,” said Smith. 

“The more people that are looking, the more we're going to learn.” 

Matthew Smith, Ph.D.

Matthew Smith is a professor in the University of Florida's Department of Plant Pathology and the curator of the Fungal Collection (Fungarium) of the Florida Museum of Natural History (FLAS). He is broadly interested in fungal ecology, evolution, and systematics, but has also worked extensively on specific fungal lineages and facilitates further research with the  Smith Lab .

Laurel Kaminsky

Laurel Kaminsky is an assistant librarian at the University of Florida's Marston Library and a lichen researcher. Her research focuses on the taxonomy of lichen and fungi taxonomy in Florida, with a particular interest in forest health monitoring with lichens.

This story was produced by  Isabel Yianilos , a student  environmental communicator  with the UF Thompson Earth Systems Institute (TESI). TESI's mission is to advance communication and education about Earth systems science in a way that inspires Floridians to be effective stewards of our planet. 

This story is part of TESI's student-produced  Earth to Florida  newsletter that curates the state’s environmental news and explains what’s going on, why it matters and what we can do about it.