Orange Peel Fungus

Welcome back to Mushroom Monday, your weekly look at some of PEI’s fascinating fungi. Not all mushrooms have the cap-and-stem look we tend to expect, and today’s species is a well-named example of a different format: meet Orange Peel Fungus (Aleuria aurantia).

Orange Peel Fungus is one of the cup fungi, similar to the Scarlet Elfcup we looked at last spring (you can find it here: https://www.pei-untamed.com/post/scarlet-elf-cups). Orange Peel Fungus’ most eye-catching feature is its bright colour, which does indeed make it look like the leftovers from someone’s fruit snack.

This mushroom’s orange pigments are due to the same chemicals that give carrots, sweet potatoes, and orange autumn leaves their colour: carotenoids. In plants, carotenoids play essential roles in photosynthesis and protection from sunlight. Many animals – including humans – need carotenoids to make necessary nutrients such as Vitamin A.  

Fungi don’t photosynthesize or need Vitamin A, so why the carotenoids? These colourful chemicals help protect the mushroom from the sun’s UV rays and are important antioxidants. In some types of fungi, carotenoids serve as the building blocks of pheromones needed to send out mating signals (remember that fungi are more closely related to animals than they are to plants!).

Carotenoids may be the most obvious biochemicals in Orange Peel Fungus, but they’re not the only ones. This mushroom also contains ‘Aleuria aurantia lectin’, which has several practical pharmacological applications.

Lectins are proteins that bind to carbohydrates, and Aleuria aurantia lectin binds specifically to a sugar called fucose. Fucose can be an indicator of inflammation and cancer, and so Aleuria aurantia lectin is being studied for its potential to improve early detection of cancer and other diseases. Fucose also play a role in certain types of allergies, and Aleuria aurantia lectin may have a future role in allergy treatments.

Orange Peel Fungus is commonly found on hard-packed soils (including along roads and trails) and will sometimes pop up in garden mulch. It is an edible mushroom, though it would be hard to collect in any quantity and is said to be fairly bland (I didn’t bother trying it). I suspect it would be best as a unique and colourful garnish rather than a side dish of its own.

As with many of the mushrooms in this series, Orange Peel Fungus is a decomposer, providing important nutrient cycling and waste disposal roles; it may also form mutually beneficial relationships with nearby trees. Unlike the spring-fruiting Scarlet Elf Cup, Orange Peel Fungus is most common in fall, so keep your eyes ‘peeled’ for it along the trails of PEI Untamed!