Ever since Elias Fries published his three-volume Systema Mycologium (1821-1832) the term ‘agaric’ referred only to cap and stem mushrooms with gills. Rolf Singer, author of The Agaricales in Modern Taxonomy (1951-1986), organized the order Agaricales into three groups: the Agaricales, the Boletales and the Russulales, groups which continue to be accepted based on molecular studies as the following clades: the eurgarics, the bolete and the russuloid. Molecular analysis has shown that some cap and stem gilled mushrooms such as Hygrophoropsis aurantiaca and Paxillus involutus are related to the boletes, which are in the Boletales order. Other fungi, which look completely different from our conception of agarics, such as Fistulina hepatica, both larger and small puffballs and some coral-like clavarioid fungi, actually belong with the Agaricales. Although there continues to be a huge overlap between the old and new sense of the terms agaric and Agaricales, in light of the recent placement of some non-gilled mushrooms in the Agaricales, clearly the two terms no longer imply synonymy.
The photos included within the Agaricales are distributed among twenty-eight different families in accordance with the current thinking. You will note that many of the most recently accepted names are different from those we learned about in our field guides. To make it easier for you to learn the new names, I have included in parentheses the older names within their newly assigned families. Over the years, expect more names to change and family relationships clarified.
Some of the families listed below have numerous species in our area of northeast North America. Others have few. To explore all the included fungi, click on each family and then progress through the images in it.