November Salt Spring Island Fungus of the Month: Hygrocybe singeri

November's fungus is Hygrocybe singeri, the colourful Western Witch's Hat mushroom. It has a bright red, orange, and yellow pointed cap and a yellow-orange stem. It doesn't actually look much like a witch's hat; it looks like a little drop of autumn.

observation by chloesj

However, it turns black wherever it is touched. In this photo, you can see the black marks forming on the stem where fingers touched it:

observation by corvi

The blackening is caused by a chemical reaction between chemicals inside the cells of the mushroom and oxygen. Handling the mushrooms "bruises" it and breaks open the cell walls so oxygen can get into the cell and react with the blackening chemical. Many mushrooms have chemical reactions that turn them blue or red when touched, but mushrooms that turn black when handled are fairly rare.

As the mushroom ages, the same process gives it black splotches; eventually, it becomes entirely black, and would make an excellent hat for a very small witch.

observation by caladri

Despite how common, obvious, and colourful it is, this species is pretty mysterious.

• It is found in the Pacific Northwest and in South America, but not anywhere in between.
• It always seems to be found with moss, but we're not sure what their relationship is.
• It has so far proved impossible to grow in a lab.
• Chemical analysis of its nitrogen indicates it is probably getting the nitrogen it needs via parasitism, but we don't know who it's stealing from. Plants? Fungi? We don't know.

observation by caladri

I am posting this quite belatedly, and it is too late to see any more Hygrocybe singeri this year, but they'll be back next fall. We may not get a lot of colourful leaves in autumn here, but sometimes the mushrooms make up for it.

Posted on January 30, 2020 04:38 AM by corvi