HI THE AGARICACEAE OF MICHIGAN 



stem as well as the young gills are said to be dark 

 violet. The FLESH is characterized in some species by 

 changing to a reddish color in age, e. g., /. pyriodora Bres., 

 I. repanda Bres., /. trinii Bres., /. incarnata Bres. and I. 

 l)0)igardli Weinn. Some of these have not been found here. The 

 SPOKES are of great importance in the diagnosis of species. They 

 may be spiny, angular or smooth. For the convenience of the 

 student, each section may therefore be divided into the rough-spored 

 and the smooth-spored species. Some authors have gone so far as 

 to suggest the use of this character to establish genera. In some 

 species, however, the spores are scarcely angular, i. e., they are in- 

 termediate between the smooth and angular shapes ; an example of 

 this condition is /. decipiens. In two of our species, I. calospora 

 and /. asterospora, the spores are spiny, i. e., the surface 

 of the spores is covered with slender, rod-like tubercles 

 producing a pretty effect when seen under the microscope. Even 

 the smooth spores often vary sufficiently in size and shape so as 

 to provide means for the identification of species. CYSTIDIA are 

 present in many species on the sides and edge of the gills ; they are 

 usually ventricose-lanceolate, mostly obtuse and covered at the apex 

 by crystal-like deposits. In other species the cystidia are lacking, 

 and only the edge of the gills is provided with differentiated 

 structures; these are inflated-rounded at the apex in the form of 

 obclavate or saccate, sterile cells, somewhat longer than the basidia. 

 Kicken has used the rough and smooth characters of the spores, 

 and the presence or absence of cystidia in such a way as to group 

 the species under three divisions: (a) those with rough spores; 

 (b) those with smooth spores and cystidia and; (c) those with 

 smooth spores and without true cystidia. I have preferred to 

 retain the more natural Friesian arrangement, modified so as to 

 use the spore character under the sections. 



The species included below have been interpreted from the point 

 of view of the eminent mycologist, Ab. Bresadola, who has revised 

 the older conceptions, and cleared up the complicated mass of 

 synonyms for the European forms. The recent work of Ricken, 

 which is also based on Bresadola's opinions, has helped not a little 

 to arrive at definite conclusions. 



