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Marshmallow Polypore - Irpiciporus pachyodon

Good afternoon, friends,

This week's mushroom is Irpiciporus pachyodon, previously known as spongipellis pachyodon, and commonly known as the marshmallow polypore. We're piggy-backing off last week's lion's mane and looking at another white, "toothed" mushroom. This mushroom was found on 10/6/2021 in the ramble. The other mushroom growing in the picture is of the genus Stereum.


I. pachyodon grows summer through fall and can be found across North America, Europe, and Asia. I put the term toothed in quotes because it is actually a poroid mushroom (spores are released from pores, typical of polypore mushrooms). As the mushroom ages the pores breakdown and create the appearance that it is a toothed mushroom similar to last week's lion's mane.

I. pachyodon is saprobic, but it can also cause a white rot in the heartwood of living hardwoods - usually oaks. In living trees, the heartwood serves as physical support and can be discolored by tannins the tree produces to fend off fungal and insect infections. While we learn about fungi it's also important we understand a few aspects of tree anatomy; it may be helpful to reference the attached image for this next section.

Heartwood diagram

Heartwood and sapwood are both composed of xylem cells - but all of the cells in the heartwood are dead as are more than 90% of the cells in the sapwood. Most of a tree trunk is composed of dead cells. The xylem cells that are living (in the sapwood closer to the exterior of the trunk) bring water/sap up, and only up, from the roots. There are also phloem cells toward the exterior of the trunk that transport nutrients both up from the roots to the branches, and down from the leaves to the roots. I like to use the mnemonic device phloem = food to help remember the functions of these cells. Sandwiched between the living xylem and phloem cells is the cambium which consists of cells responsible for creating new xylem and phloem cells. The image is from the fifth reference which has more details on tree anatomy without being overwhelmingly scientific - striking a balance I hope I didn't miss here.

Personal Update

I have some bittersweet news. As some of you may know, I have put in my notice of resignation at the Central Park Conservancy. My last day is 12/1/2021. I've accepted a position as Assistant (to the) Ecological Manager at Manitou Point Preserve in Manitou, NY. It's a 200 acre preserve right on the Hudson that is privately owned but has 129 acres of trails that are open to the public.

The important information is that Mushroom Monday will not stop, and in fact, will just expand to feature mushrooms from outside of the park. I still have a stockpile of Central Park mushrooms, and would like to hit 100 species, but I may start to pepper in fun mushrooms that have found me outside of this great 843-acre rectangle. I'll still be living in the city for the time being so I hope to do more mushroom walks in the park, and when the time comes, we can even look at doing walks up in Manitou. I've loved my time in Central Park and I'm quite stoked about this new opportunity.

I look forward to continuing to learn and grow together,



1) Kuo, M. (2010, March). Spongipellis pachyodon. Retrieved from the MushroomExpert.Com Web site:

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