Mushrooms that change color

     Have you ever heard that you can tell if a mushroom is poisonous or not but rubbing it on a silver spoon and seeing if it discolors the silver? Maybe you've heard that if a mushroom stains blue it will make you hallucinate if you eat it, or if it stains yellow, it's no good.

There's a lot going on with color reactions and mushroom identification, and while some of these commonly repeated ID tips are based on the truth, it's generally a really bad idea to trust your life to them. However, a little research reveals that color changes can tell you a lot about what you're dealing with, and they tend to be a major identifying characteristic when present.

While the myth about the silver spoon is totally false, there are certain chemical reagents you can drop onto the flesh of a mushroom   that will react with chemicals in the mushroom and cause the spot to change colors, greatly aiding you in identification. for example certain poisonous species of the genus Agaricus (related to the common "grocery store" mushroom) stain yellow when they come into contact with a solution of KOH (potassium hydroxide). Some situations require you to find out if the spores are amyloid by testing them with Melzer's reagent and seeing if they turn a dark blue or black color . Even ammonia can be used to observe a color reaction in some Boletus species.

It's true that many psychedelic mushrooms stain blue when bruised, due to the oxidation of  psilocybin into the psychoactive compound psilocin, but not all hallucinogenic mushrooms stain blue, (Amanita muscaria for example) and not all blue staining mushrooms are psychoactive.

Panaeolus cyanescens, a blue staining psychoactive mushroom.

 Boletus satanas is a beautiful blue staining member of the same genus as the edible king bolete, that is dangerously poisonous. In fact a number of the blue staining boletes are inedible and beginners should generally stay away from blue staining (or red pored) boletes unless they have ID'd them to the species. Personally I don't eat anything that I am not 100% sure about, although sometimes I have been known to make exceptions for the odd unidentifiable subspecies of a known good edible.

Boletus zelleri is an edible blue staining bolete.

Some of the local Tahoe King Boletes have a tendancy to stain reddish-purple that seems to be unknown of outside of my own experience,  They key out almost perfectly to Boletus grandedulis, with two exceptions, the tedency to stain vinaceous, but only near the outermost parts of the cap and stalk, and a slightly sour taste.

Boletus grandedulis?

It could be an undiscovered subspecies, there are definitely plenty out there that haven't been described yet, or perhaps it's just some environmental factor. Hard to say, but I can tell you from personal experience, it's edible, although not as good as the not sour kings that grow elsewhere.


Many mushrooms of the genus Lactarius are known to stain when their damaged tissues or even the drops of latex that they exude are exposed to the air:

This edible species is Lactarius paradoxus, it's especially stunning with the combination of blue cap and stem, pink gills, and green stains.

This is Lactarius deliciosus, another green staining edible milk cap, and it's a great example of how you can't always depend on staining reactions. This one also wasn't putting out milk, as you can see by the broken part of the gills.

There are also purple staining Lactarius, and Lactarius that have yellow staining latex that are known to be poisonous, but as you can see in the above photograph, it is crucial to identify your mushrooms to the species level, because latex and staining reactions can both be absent, especially in dry weather.

Among the genus Agaricus, there are also varied staining reactions. I already mentioned that some stain yellow when exposed to KOH, there is another that stains green with KOH, and many stain yellow just on exposure to the air. The common grocery store button, Agaricus bisporus, tends to stain reddish, then brown after a couple minutes.

There is an edible species, Amanita rubescens that stains red also, although I don't recommend you try them, as Amanita is also known for being the family with many of the most deadly poisonous mushrooms in it. Amanitas are easy to avoid, and I've heard tales that they hybridize with each other, so as far as I'm concerned it's worth it to just stay away.

Amanita muscaria var. formosa, the yellow fly agaric, is a yellow version of the classic "red with white spots" hallucinogenic Amanita.

There are so many different kinds of color staining mushrooms, it's practically impossible to identify a mushroom on a staining reaction alone, in fact it's also practically impossible to ID a mushroom on color. There are a few exceptions to the rule, an orange cup fungus that stains blue is going to be the blue staining orange peel fungus, and Lactarius paradoxus is probably the only bright blue mushroom with pink gills and green stains, but the fact is, if you want to know your mushroom, you've got to get to know your mushroom, and the way you do that is by learning to observe every little detail.

Here's another picture of L. paradoxus for the road:

happy hunting!