Tom Volk's Fungus of the Month for November 1999

This month's fungus is Rozites caperata, the gypsy mushroom, reported to have antiviral activity.

Also be sure to look at some seasonal Thanksgiving fungi -- check out my popular and newly revamped
Fungi that must be overcome to have a traditional Thanksgiving dinner.

Rozites caperata, the gypsyThis month's fungus is a delicious edible mushroom known as the gypsy. (I haven't been able to figure out the origin of this name-- anyone know?-- maybe it's because they tend to be scattered all around a forest?). Rozites is named in honor of a European mycologist Ernst Roze, who worked in the early 1900's. The specific epithet caperata means wrinkled-- older specimens of this mushroom often have a wrinkled cap. I've also heard this referred to locally as the "powdered sugar mushroom" because of the bloom or sheen of white fibrils on the cap, as shown in the picture below and to the right.

Rozites is a member of the Cortinariaceae, and appears to be closely related to the genus Cortinarius. The spore color, shape and size are all similar, the ecological habitat is similar (mycorrhizal with pine and oak). Both genera have attached gills, and the only major difference is that Rozites has a membranous ring instead of the cobwebby partial veil remnants in Cortinarius. It's especially close to Cortinarius claricolor, which I have never seen --but is nicely pictured in Mushrooms of Northeastern North America (Bessette, Bessette, and Fischer). Rozites caperata, the gypsyRozites a fun mushroom to find. It's usually a lot of work to collect them as they don't normally occur in large cluster-- one here, one there, a few over there. They grow in northern zones throughout the world, especially with conifers, but sometimes in mixed hardwoods such as oak, birch, and aspen. Some years they are very abundant and some years they are scarce. I don't think I saw even one this year. It has a very delicious flavor, kind of spicy, a bit like cinnamon-- to go with the cinnamon-brown spore print perhaps? Besides confusing this with Cortinarius species, you might mistake it for an Agaricus, but Agaricus species have chocolate brown spores and free gills. Pholiota species may be similar but have purple-brown spores and normally grow on wood. There are no other accepted species of Rozites in North America to my knowledge. Meinhard Moser (1953) has accepted a few other species in Europe, although I have not seen recent reference to these.

Rozites caperata has recently gotten quite a bit of publicity for its reported antiviral properties. According to this press release, Curtis Brandt and Frank Piraino, two research scientists from the University of Wisconsin-Madison,

"...have found that extract from the mushroom prevented herpes simplex virus types 1 and 2 from growing in test tubes and it reduced the severity of herpes-related eye disease in mice. It blocked influenza A, chicken pox and a respiratory virus.... The active part of the mushroom, a compound they call RC-183, has been patented."

I have been mushroom hunting with Frank several times, and helped to collect Rozites for this project, so it's fun for me to see how all this has paid off. The compound is on its way to clinical trials in humans, so it will be interesting to see if this initial success can be translated into something for human use.

One other important lesson from this finding is that, although tropical rainforests get most the publicity about being possible sources of new drugs and useful compounds, there is quite a bit we don't yet know about the fungi that grow in out own backyards. There should be more research on the thousands of species of fungi right here where we live, many of which have yet to be described to science.

If you have anything to add, or if you have corrections or comments, please write to me at

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