Tom Volk's Fungus of the Month for September 1999

This month's fungus is Cortinarius semisanguineus, the half-blood-red Cortinarius

Cortinarius semisanguineusThe beautiful mushrooms to the left are Cortinarius semisanguineus, also known as Dermocybe semisanguineus. Some mycologists consider Dermocybe to be a distinct genus and some consider Dermocybe to be a subgenus of Cortinarius. Its major claim to fame is that it is an important mycorrhiza former with pines and other members of the Pinaceae, and that it's much sought after by people who dye wool with mushrooms. What? --- DYE WOOL ?? There is a very interesting "subculture" of people who are interested in mushrooms and other fungi mainly because they can dye wool with them. Pat BrannenBelow and to the right is my friend Pat Brannen, of Albuquerque, New Mexico, wearing her name tag with various pieces of wool dyed with various fungi. I believe the third from the left is dyed with Cortinarius semisanguineus gills. The cap and stem dye wool a muted brown. It's very interesting to see what colors come out of different mushrooms. Many are not what you'd expect at all. Surprisingly many brightly colored mushrooms won't dye wool at all-- fungi like chanterelles, Laetiporus sulphureus, red Russulas, and bright colored Amanita species like Amanita muscaria have no dyeing ability at all. Another important point to remember is that we're talking about dyeing with mushrooms not dying from mushrooms...

Here's a couple links with more information on dyeing wool with fungi.

This fungus is not known to be a poisonous mushroom, but is not considered edible. I'll have more to say on that later. Cortinarius is a very large genus of mycorrhizal mushrooms, with over 400 described species. Determining the correct species is considered to be very difficult. There are not many people in the whole world who know the species, so don't feel bad if you try to key out a Cortinarius species and you can't get it to fit the description exactly. The species concepts are difficult at best. Some of the characters that are important are the relative sliminess and viscidity of the stipe vs. the cap, the color of the buttons and their changing color as they mature, and the size and shape of the stipe and cap.

Cortinarius atkinsonianusAlthough the species of Cortinarius are difficult, it's rather easy to determine that a specimen belongs in the genus. Cortinarius species. Characteristically they have a cinnamon brown spore print, grow on the ground forming ectomycorrhizae with pines and oaks, and have a cobwebby veil called a cortina, shown in yellow to the left. The cortina is thought to protect the developing gills of the mushroom. It usually tears off as the mushroom matures, but you can usually find remnants of it on the stalk if you know what you're looking for. The mushroom below and to the left is some relative of Cortinarius alboviolaceus, one of the most beautiful in the genus because of its lavender color. However, there are a dozen or so lavender colored species. They're not all C. alboviolaceus, as some field guides would have you believe.

stages of Cortinarius development To the left are several stages in the development of one of these lavender species. You can see the intact cortina protecting the gills on the specimen on the left and see how the cortina breaks as the mushroom enlarges. You can barely see the remnants of the cortina on the mature mushroom, although in some species it is much more apparent than shown here.
One of the dangers of these purple species is that they can be confused with the wood blewit, Clitocybe nuda. It's relatively easy to tell the difference however. Clitocybe nuda has a buff to pink spore print and no annulus on the stalk, while Cortinarius species have a cinnamon brown spore print and a cortina, or at least remnants of a cortina. but why worry about the confusion? Well some species of Cortinarius have been show to contain a toxin called orellanine. Orellanine can destroy the liver and kidneys, and can be "mild to fatal" in its effects. Symptoms do not appear until 3-15 days after ingestion of the mushroom, so often doctors may misdiagnose this as something else not connected to the mushrooms. The toxin has been shown to occur in Cortinarius orellanus and a few related species, but relatively few of the 400 or so species of Cortinarius have been studied to see whether they contain the toxin. I do not recommend eating any Cortinarius species. Just enjoy their magnificent colors and sometimes great abundance. I've been to forays where we found 50 unidentifiable species of Cortinarius !
Cortinarius zakii I hope you enjoyed learning something about Cortinarius semisanguineus and other member of the genus, such as this Cortinarius zakii to the right. Just in case you were wondering there is also a species called Cortinarius sanguineus, which has a blood red color on both the cap and the gills. A similar colored species in the southeast US is called Cortinarius marylandensis. All members of this section Dermocybe are much sought after by wool dyers. They are important ectomycorrhizal fungi and are fun to see and collect. If you're particularly lucky you may have a friend who will dye some wool for you.

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

This page and other pages are © Copyright 1999 by Thomas J. Volk, University of Wisconsin-La Crosse.

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