Basic information on a mushroom guide includes the mushroom's size, color, shape, smell and typical habitat. Other information includes the type of structure in which the mushroom stores its spores, the surface texture of its cap, its spore print color, and whether or not the mushroom has an annular ring. Mushroom guides also typically feature information about whether the mushroom is edible, inedible or toxic.
Despite being the most obvious features of a mushroom, a species' size, color, shape and similar overt characteristics are not especially useful when making an identification. Many mushroom species exhibit remarkable similarity in these features.
The structures in which the mushroom stores its spores are vital characteristics mycologists use when making an identification. Most mushrooms store their spores in gills, while others store these reproductive structures in spongy tubes and still others store them on long, dangling teeth.
A mushroom's spore print color is one of the most useful tools for identifying a species. To take a spore print, mycologists cut off and discard the mushroom's stem, known as a stipe, and place the cap on an index card with the gill side facing down. After several days, millions of spores fall from the cap onto the card, producing an easily identifiable color. For absolute certainty, mycologists can analyze spore prints under a microscope.