Chemical tests in mushroom identification

Chemical tests in mushroom identification are methods that aid in determining the variety of some fungi. The most useful tests are Melzer's reagent and potassium hydroxide.

Household ammonia can be used. A couple of drops are placed on the flesh. For example, Boletus spadiceus gives a fleeting blue to blue-green reaction.

Iron salts are used commonly in Russula and Bolete identification. It is best to dissolve the salts in water (typically a 10% solution) and then apply to the flesh, but it is sometimes possible to apply the dry salts directly to see a color change. For example, the white flesh of Boletus chrysenteron stains lemon-yellow or olive. Three results are expected with the iron salts tests: no change indicates a negative reaction; a color change to olive, green or blackish green; or a color change to reddish-pink.

The Meixner test (also known as the Wieland test) uses concentrated hydrochloric acid and newspaper to test for the deadly amatoxins found in some species of Amanita, Lepiota, and Galerina. The test yields false positives for some compounds, such as psilocin.

Melzer's reagent can be used to test whether spores are amyloid, nonamyloid, or dextrinoid.

This test is normally performed on white spored mushrooms. If the spores are not light colored, a change will not be readily apparent. It is easiest to see the color change under a microscope, but it is possible to see it with the naked eye with a good spore print.

In the genus Lyophyllum the lamellae usually turn blue with the application of para-Dimethylaminobenzaldehyde (PDAB or pDAB).

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