INTRODUCTION. 



The Agaricaceae constitute a rather large family of the 

 Basidiomycetae and are commonly known as the "gill fungi." 

 The family is characterized by having the spores borne on club- 

 shaped basidia arranged in a definite layer known as the 

 hytneniuin, which covers a number of radiating plates, the 

 lamellae or "gills", suspended from the lower surface of the 

 pileus, or cap. A stipe, or stem, is usually present, but may be 

 wanting. 



Many of the species are edible, and some are considered 

 a great delicacy. Others are poisonous, and may cause serious 

 illness or even death. A few are parasitic upon certain higher 

 plants, notably upon the roots or trunks of trees, when they 

 may cause extensive injury to the timber. Many are beautifully 

 colored, red, yellow, purple, brown, white, etc., or quite large, 

 or otherwise striking in appearance. For these reasons and 

 others these plants are interesting objects of study. 



The present paper is essentially a preliminary report on 

 the Agaricaceae of Ohio and consists of keys to the genera and 

 species reported as occurring within the state. A glossary of 

 descriptive terms and a bibliography of the literature pertaining 

 to the Ohio species and other works, wdiich will be found help- 

 ful to the student, are included. 



The list of species has been made up from the works (see 

 bibliography) of I.ea, Morgan, Hard, Lloyd, Peck, Berkeley, 

 Kellerman and Montague. Besides the species thus published, 

 the list has been augmented by reference to specimens in the 

 herbarium of the New York Botanical Garden, the herbarium 

 of the state botanist of New York, the herbarium of the Ohio 

 State University and by the collections of the writer. 



Thomas G. Lea collected in southwestern Ohio, 1834-1844, 

 and sent his specimens to Rev. M. J. Berkeley, in England, who 

 described a number of new species from them. Others were 

 referred to existing species. Morgan, a number of years later 



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