This summer, the Native Plant Garden was full of flowers, growth, animals, people, and learning. UW–Madison students Holly and Kate joined me and dozens of garden volunteers to plant, weed, and monitor the garden. I appreciate their energy, curiosity, dedication, and collaborative spirit. Some days they experienced excessive heat and humidity, poor air quality, mosquitoes, chiggers, and ticks. Every day they observed garden details and patterns and found new questions to explore – so many great questions! As they return to their classes this month, I hope their summer garden experience deepens their academic work. They wrote this article, which reflects one of their many shared interests: fungi in the garden. Thank you, Holly and Kate!

– Susan Carpenter, Native Plant Garden curator

This summer we have had the amazing opportunity to work and learn in the Native Plant Garden. We came in excited to learn about native plants but quickly became fascinated by the diversity and ecological roles of many organisms in the garden.

While the flowers are pretty and the critters are cute, there is another important member of the Native Plant Garden’s ecosystem – fungi! Fungi have many important roles in the garden; some work to decompose dead and dying plant matter, some create mutually beneficial relationships with other organisms, and some function as pathogens.

During our exploration of the gardens, we discovered new fungi nearly every day. Many of these are saprobic in nature, meaning they break down dead organic matter and return nutrients to the soil (known as nutrient recycling). Without saprobes replenishing the soil, our plants would lack many of the essential nutrients they need to grow and reproduce. These fungi come in countless interesting variations.

In the Maple-Basswood Forest we stumbled upon the adorable bird’s nest fungi (Crucibulum laeve): tiny cups resembling a nest and eggs that decompose mulch and dead leaves. The white jelly fungi (Ductifera pululahuana), found on dead wood and sticks throughout the gardens, look like little brains! And in a playful display, earthstars (genus Geastrum) in the Native Tree and Shrub Display reveal a star-like shape as their triangular rays spread downwards to reveal a bulbous spore sac.

However, the role of fungi in the garden extends far beyond nutrient recycling. Many species form mutualistic partnerships with the roots of our beloved native plants – a relationship known as mycorrhizal symbiosis. While this interaction may not be apparent to us humans admiring the plants and mushrooms from above ground, there is an incredible exchange occurring silently below our feet.

When we spot a mushroom, we’re actually seeing the fruiting body (reproductive structure) of the fungus. The main vegetative body of mushrooms, however, is made up of thread-like structures called hyphae that spread out underground. In mycorrhizal symbiosis, these hyphae directly connect to the roots of plants. The plant provides the fungus with sugars from photosynthesis, and in return, the hyphae act as an extended root system for the plant, increasing water and nutrient uptake from the soil.

While planting in the Maple Basswood Forest, we recently spotted a striking ruby bolete mushroom (Hortiboletus rubellus) peeking through a layer of leaf litter. This mushroom is known to form an ectomycorrhizal mutualism (a type of mycorrhizal mutualism in which the fungal cells surround, but do not enter, the host plant root cells) with the roots of beech and oak trees, which helped us solidify our identification. Other ectomycorrhizal mushrooms we’ve observed in the Native Plant Garden include the white saddle fungus (Helvella crispa) and many species of brittlegills (genus Russula).

While many species of fungi act as mutualists and decomposers, others take on a very different role in the garden as plant pathogens. A fungal plant pathogen infects and derives nutrients from a living host plant, often interfering with the plant’s ability to grow and thrive. While these fungi can harm their hosts, they also play an important role in ecological balance.

In late spring, we spotted a wide array of bright orange rusts (order Pucciniales) on garden plants including roses, serviceberries, hawthorns, junipers, and even on the weedy buckthorn. Perhaps the most perplexing example was the dripping, globose cedar-apple rust (genus Gymnosporangium) found in the branches of a juniper tree. Fungal plant pathogens are prevalent throughout the growing season and are yet another example of the beautiful diversity of life supported by the Native Plant Garden.

Make sure to come pay a visit to the native plants as soon as the late summer blooms begin. But when you do, don’t forget to keep an eye out for the beautiful diversity of fungi nestled within the plants – infecting them, supporting them, and breaking them down.

– Holly Johnson and Kate Leonard, UW–Madison students and summer garden staff