Macroscopic, microscopic and chemical observations are all used to identify mushrooms. Size, color, shape, odor, taste, texture and other surface characteristics as well as habitat can be determined without special equipment. How the mushrooms react to various chemicals may also be important in identification. Criteria observed through microscopic examination include the structure of the cap cuticle (surface) and the orientation of the hyphae (fungal cells) in the gills.
Mushroom spores (reproductive unit) provide information both macroscopically and microscopically. The size, shape and ornamentation of spores are determined through microscopic examination. A spore print provides information about spore color if a microscope is not available.
Mushroom color is influenced by environmental factors and age. Thus the color of a mushroom and its gills (or pores) can vary. Spore color is more constant and less affected by the environment. Each individual spore is too small to see with the naked eye. However masses of spores are visible in a spore print. To make a spore print cut the stalk (stipe) off of the mushroom cap close to the base. Place the cap on a piece of white paper with the gills or pores facing down and cover with a glass or bowl to prevent air currents. After several hours or overnight there should be a spore print.
Spore color is necessary for the identification of many mushrooms. Identification guides generally suggest that a spore print always be taken if the mushrooms are to be eaten. For example: Several of the most deadly or hallucinogenic mushrooms (Aminitas) can easily be confused with some members of Agaricus, a genus that includes both the cultivated mushroom and the edible meadow or field mushroom (Agaricus campestris). The spore print is valuable because Aminitas all have a white spore print while the meadow mushroom has a chocolate-brown print. Do not eat that “meadow mushroom” if its spore print is white!!
These chocolate brown meadow mushroom spore prints were made with meadow mushrooms growing in our yard and pastures (Lookout CA) following recent rains. The one print is much lighter because I did not let it sit and accumulate spores as long.