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Orange Peel Fungus - Aleuria aurantia

Good evening, friends,

This week we're dipping into the fall fungus archive to look at the Orange Peel Fungus (Aleuria aurantia). I thought I had stumbled upon the remnants of a youth soccer game when I saw what looked like discarded orange peels while on a walk this past October in Fahnestock State Park. Even more surprising than the scraps of a tropical fruit, these were the living fruiting bodies of a fungus. The little black dots you see on the specimen below are tiny insects, springtails I believe. That's just one of the many interesting features found in and around this marmalade-colored mushroom.

Aleuria aurantia

Fun Facts

This fungus is an ascomycete - a particular phylum of fungi separate from the familiar basidiomycetes we normally look at. One unique aspect of ascomycetes are that they use ballistics to release spores, whereas the basidiomycetes rely on gravity for dispersal. From my understanding, the fruiting body of an ascomycete isn't technically a "mushroom" and can properly be classified as an ascocarp. Regardless, the spores are said to leave the fungus at speeds up to 25 meters per second (Reference 3). Unbelievable.

What's also interesting about these "cup fungi" (rubbery ascocarps that look like a dish or pig's ear - in the Order Pezizales) is that you can see them visibly release their spores if you give them a little puff of encouragement. If you come across these or other cup fungi blow on them like a birthday candle (a singular candle, not a whole cake, you typically don't have to blow very hard). I can't embed videos in this email (that's what I tell myself, it's probably more likely I just don't know how to) so instead I provide you this link. This large, spontaneous spore release is thought to be triggered by a change in humidity from your breath.

Aleuria aurantia

Aurantia comes from the Latin Aurantius which means "orange-colored". I also saw Aurantia can mean "golden" which checked out in my opinion because, if you remember, Au is the chemical symbol for Gold on the periodic table of elements. Aleuria means "flour" in Ancient Greek and is thought to relate to the appearance of having a dusting of flour on the outside of the cup. These little orange peels are alleged to be edible but I can't imagine them cooking up well since they're so brittle.

Aleuria aurantia


A. aurantia is generally thought to be saprobic, growing from dead organic material on the forest floor, however t it may also form mycorrhizal relationships with trees - more research is needed. It seems to prefer disturbed soil on the sides of trails and will even grow in landscaped environments. The ascocarps grow late summer through fall east of the Rockies and from late autumn into the winter months on the west side of the continent. The fungus can be found on every continent besides Antarctica.

There are a surprising amount of species that look similar, including those in the genus Caloscypha. Both are rubbery and brittle, but Caloscypha fruiting bodies discolor a greenish blue as they age. It's also important to note that A. aurantia doesn't have a stipe (stem), like Sowerbyella rhenana, and instead grows flush with the ground attached only by a tuft of mycelium. A last interesting note is that only the interior of the fruiting body has asci (the plural of ascus) which are the cells where spores both form and are ejected. This means the vibrant orange interior is where spore dispersal occurs, and it seems the whitish-orange outside is more of a fashion statement than functional organ.

Aleuria aurantia


Well folks, the suits at Intuit weren't content with the money I incredibly begrudgingly give them for their online tax filing program and are now trying to squeeze me for Mailchimp money. The provisions for their free newsletter program are changing on 3/10/2023 and I'm going to have to find a new platform for Mushroom Monday distribution. I'm leaning Substack based on previous recommendations, but if you have any ideas I'm all ears. Wherever we go, Mushroom Monday will endure. In other tech news, I have been in touch with what are probably internet scammers about the rights to That's right folks, we might drop the hyphen. There's going to be a lot of shaking and shifting in the next couple months, buckle up.

Heading to New Hampshire on Thursday and I'll be on the lookout for next Monday's mushroom while I'm up there.

Same time next week to see what I find,



1) Kuo, M. (2020, January). Aleuria aurantia. Retrieved from the MushroomExpert.Com Web site:


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