Cystoderma aureum

September 5, 2022

Good evening, friends, and happy Labor Day.

This week we return to the Rockies to get acquainted with the golden bootleg mushroom (also known as the golden cap, and for those so inclined Cystoderma aureum, formerly Phaeolepiota aurea). This was one of the first mushrooms we found in Telluride, and it was growing in the grass on one of the ski slopes at the top of the town gondola (a neat mode of public transportation). It was described by the local mushroom folks as an uncommon find, but golden caps had been seen a few times this summer – probably due to all the rain they’ve received.

Fun Facts

Cystoderma mushrooms are known as “powder caps” because they have dust-like granules on their caps and stipe – enough to have some residue on your fingers after you’re done handling one. Cystoderma comes from Ancient Greek, where kystis means pouch and derma means skin. Aurea, in latin, means gold and references the color of the mushroom (remember, gold is Au on the periodic table of elements) . Another distinct feature was the difference in texture between the smooth, golden stipe above the ring (aka the annulus, the remnants of the partial veil) and the rough, powdery membrane below (the bootleg, I suppose).

Medicinal compounds (polysaccharides) in extracts of C. aureum mycelium have been found to possess anti-cancer properties. When injected into a group of white mice, it reduced the growth of two different types of tumors – Sarcoma 180 and Ehrlich solid cancers – by 100% (Reference 2). It’s hard to believe anything, even the most magical of mushrooms, can be 100% effective, but it certainly looks good on paper. Now we just need some volunteers that want to get jabbed with a little golden bootleg extract…

These mushrooms were initially sought after as tasty edibles, but recent studies have shown that they possess high levels of hydrogen cyanide and cadmium. When consumed, they’ve been known to cause gastrointestinal distress in some – but perhaps that’s just folks having a harsh time with the heavy metals. If you find yourself hungry and in a pinch, apparently some of the cyanide cooks out when you heat it.


There were at least ten mushrooms growing in this gregarious fruiting when we stumbled upon them, and as it turns out they typically grow in these clustered bunches. It’s not fully understood whether they’re saprobic or mycorrhizal, but the the leading belief is that they’re saprobic on dead organic material near conifer trees. This patch was found on a ski slope, amongst grass and moss close to conifers (I have to admit I felt naked out there not knowing the trees – unable to tell a lodgepole pine from an Engelman spruce). The mushrooms grow mid-summer through mid-fall (August through November). While known to be uncommon or even rare, the fungus seems to have a wide range of distribution as the mushrooms pop up throughout temperate forests of the northern hemisphere. They’ve been found in Asia, Europe, and on both coasts of North America as well as the Rocky Mountains.

We thought the odor was rich, nutty, and cheesy, but the mushroom is described in a lot of places as possessing a bitter almond-like odor. Per the CDC, Hydrogen cyanide has a bitter almond-like odor as well, so perhaps you’re just smelling the cyanide. Keep in mind the sense of smell is pretty subjective so it’s not always the best identifying characteristic. Physical traits, in this instance, are much better for identifying C. aureum. The photo above shows a bisection of the cap – just take a look at the color difference between the golden gills and the white interior of the cap. Now peek at the photo below where you’ll notice the very significant and robust partial veil. If you were to brush your finger along that partial veil you’d get it covered in golden dust, to boot(leg).

How nice to finally get some substantial rain,