Fungi of the Carleton Arboretum

Stereum fungus by Klara Kjome Fischer ’26. Ecology: Saprotrophic.

Fungus with blue mold by Klara Kjome Fischer ’26.

Cup fungi by Nancy Braker ’81. Ecology: Cup Fungus, saprotrophic.

Tiny decomposers of leaves by Klara Kjome Fischer ’26. Ecology: Saprotrophic.

Cyathus striatus “Fluted Bird’s Nest fungi” by Esme Krohn ’24. Ecology: Bird’s Nest Fungus, saprotrophic.

Fusicolla merismoides “Deer Vomit” by Klara Kjome Fischer ’26. Ecology: saprotrophic.

Langermannia gigantea “Giant Puffball” by Nancy Braker ’81. Ecology: Puffball, saprotrophic.

Panellus stipticus “Luminescent Panellus” by Klara Kjome Fischer ’26. Ecology: Agaric, saprotrophic.

Shelf fungi by Joanne Bouknight. Ecology: Saprotrophic.

Trametes veriscolor “Turkey Tail” by Klara Kjome Fischer ’26. Ecology: Polypore, saprotrophic.

Irpex Lacteus by Klara Kjome Fischer ’26. Ecology: Polypore, saprotrophic.

Bay Polypore by Klara Kjome Fischer ’26. Ecology: Polypore, saprotrophic.

Laetiporus sulphureus by Berett Wilber ’14. Ecology: Polypore, saprotrophic.

Fungi are a kingdom of organisms, distinct from plants. They span a variety of roles, from microscopic mildews to the large, mushroom-producing fungi we’re most familiar with. This guide focuses mainly on these macrofungi. 

Lacking chlorophyll, fungi cannot photosynthesize. Instead, they use hair-like hyphae to draw nutrients from the substrates they grow on, including soil and organic matter. Fruiting bodies are created as a means of reproduction. Mushrooms are one type, facilitating the dissemination of spores. 

In their environment, fungi primarily serve as decomposers, breaking down organic matter into forms of nutrients that plants can use. Fungi can further be divided by how they associate with other organisms. What follows is a discussion of three distinct roles, one or more of which can describe a given species. A spreadsheet is then included with a listing of observed species in the Arb and additional information and resources. 

Saprotrophic Fungi

The majority of macrofungi are saprotrophs. Saprotrophic fungi feed on dead organic matter, serving an important function as decomposers. They use enzymes to break down plant matter and nutrients into forms that plants are able to absorb from the soil.

Fungal groups with this role: Puffballs, Polypores, Jelly Fungus, Bird’s Nest Fungi, some Agarics

Parasitic Fungi

Parasitic fungi live on and feed off of another organism, often to the detriment of the host. Many parasites associate with a specific host; one such example is Cedar-apple rust, which grows exclusively on these trees. In the Arb, some are very detrimental, like Dutch Elm Disease. However, others serve important functions in the ecosystem, serving to balance populations. How we view these fungi may depend on their association with plants we are trying to protect or eradicate.

Fungal groups with this role: Rusts, some Polypores and Agarics

Mycorrhizal Fungi

Mycorrhizal fungi form a mutually beneficial relationship with plants, unlocking nutrients in exchange for carbon. They grow around, or even inside of, root cells to facilitate the transfer of nutrients. The most common type in the Arb is arbuscular mycorrhizal fungi, the hyphae of which penetrate root cells, forming “arbuscules,” or tree-like structures. Ectomycorrhizal fungi, in contrast, grow around the outside of root cells, forming what is called a Hartig net. Many fungi associate with only one or a few specific plants. They may also facilitate connections between plants.

Fungal groups with this role: Some Agarics (Amanita), Earth balls, Boletes

List of Fungal Species in the Arboretum

Information about fungi found in the Cowling Arboretum is in the spreadsheet linked below. To learn more, you can also visit the Cowling Arboretum iNaturalist project, and filter search results to ‘fungi’. Our list is updated from iNaturalist, so consider uploading observations you make on the trails!

Further Information

Fungi have historically been used by people for food, medicine, textiles, and religious purposes, among others. You are most likely to find fungi in the fall, or after a rainstorm.

If you wish to identify a fungus, guidebooks such as “North American Mushrooms” (2006) by Dr. Orson K. Miller Jr. and Hope H. Miller are a good place to start; several others are cited in the spreadsheet. You can also turn to the Seek app by iNaturalist for a general idea. Please take care with these resources—remember that many mushrooms are poisonous, and the Arboretum does not allow the collection of fungi or other artifacts.

• About
• Agarics
• Bird’s Nest Fungi
• Boletes
• Earth balls and Puffballs
• Polypores
• Rusts

Learn more about the most common types of fungi by navigating between these tabs.

Agarics are a large, diverse group of fungi characterized by a cap with gills on the underside. Most found in the Arb are saprotrophic, with the exception of Amanita, which are mycorrhizal with specific plant hosts. A few act parasitically.

Bird’s nest fungi are saprotrophic, and are characterized by a cup-like fruiting body with ‘eggs’, which contain spores which are dispersed when rain drops splash into the cups.

Boletes have very specific symbiotic, often mycorrhizal, relationships. One species in the Arb is generally mycorrhizal, while another is symbiotic with a type of aphid that feeds on Ash tree roots. Many boletes have a pore surface on the underside of a mushroom cap, but the genus is varied.

These fungi have spores contained within a fruiting body that are released when the mushroom breaks open.

Polypores, also known as bracket or shelf fungi, have pores on their underside, where spores are produced. Most are saprotrophic, while some may be mycorrhizal.

Rusts are a type of fungi parasitic on specific host plants. They do not produce mushrooms, but instead may be observed as a rust-like speckled coating on a plant. Different stages of the life cycle, and different types of rusts, may vary in appearance.