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Purple-bloom Russula - Russula mariae

Good afternoon friends,

This week's mushroom is Russula mariae, the Purple-bloom russula. This is our first mushroom from the genus Russula, commonly known as brittlegills, featured on Mushroom Monday. R. mariae was first described by the renowned mycologist Charles Horton Peck (1833-1917) of Sand Lake, NY, and he named the mushroom after his wife Mary. This specimen was found on 6/28/2021 in the Ramble during the same drought-like conditions as last week's leopard earthball (Scleroderma areolatum).



R. mariae grows summer through fall in eastern North America and is mycorrhizal with oak (Quercus) trees. It's fairly easy to identify a mushroom in the genus Russula, but to identify a Russula to species is quite difficult. There are two defining characteristics of R. mariae: the velvety purple cap that is adorned with a light white dusting or "bloom" (unfortunately the cap picture I took is out of focus) and the pink/purple coloring on the stipe. Even those two "defining" characteristics can be variable - thus adding to the difficulty of getting a conclusive identification. There are other macroscopic features you can use to identify Russulas like taste and how easily the "cuticle" - the colored surface of the cap - peels off the cap itself. However, Michael Kuo of mushroomexpert.com has a problem with all these Russula identification methods because they're incredibly variable and quite obtuse. One note on taste: you can nibble on the cap of any mushroom, let it sit on the front of your tongue, and spit it out with no ill-effects. Taste can be a significant and helpful identification tool, and a good way to introduce new microbes to your microbiome. There are a group of 12 russula species known as "foetid russulas" that taste quite acrid.



One last interesting note; as the summer progresses you may encounter Monotropa Uniflora, commonly known as Ghost pipes, growing in your local woods or park. This is a plant that has evolved out of producing chlorophyll and instead gets sugars from mycorrhizal fungi which are already obtaining their sugars from trees. Where M. Uniflora is growing you can almost always look around and find Russulas growing nearby. All of the mycorrhizal fungi M. uniflora associates with are in the family Russulaceae. The general understanding right now is that M. uniflora is parasitic and is taking sugars from the fungi without contributing anything to the relationship. However, I don't subscribe to this understanding because I've heard Russulas will seek out M. uniflora in the soil, and M. uniflora could be contributing to the relationship in a way that has so far eluded human perception/understanding. Nonetheless, it is a good indicator of healthy mycorrhizal fungi in the soil when you see it.

Have a delightful week,

Aubrey


References:

1) Kuo, M. (2009, March). Russula mariae. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/russula_mariae.html

2) Kuo, M. (2009, March). The genus Russula. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/russula.html

4) S. Yang & D.H. Pfister (2006) Monotropa uniflora plants of eastern Massachusetts form mycorrhizae with a diversity of russulacean fungi, Mycologia, 98:4, 535-540, DOI: 10.1080/15572536.2006.11832656 Web site: Monotropa uniflora plants of eastern Massachusetts form mycorrhizae with a diversity of russulacean fungi: Mycologia: Vol 98, No 4 (tandfonline.com)

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