62 ELEVENTH REPORT. 



we follow Earle, three genera, will include our Michigan species and will be 

 characterized below in their proper places. 



As a ready means of identification it has seemed best to provide an artificial 

 key for the Michigan species. In this key there are included a number of 

 species which have not yet been reported, but which are known in neighbor- 

 ing states or have always been assumed to be common thruout the country. 

 The difficulties of identification have often been increased by the use of keys 

 to the old subgenera. Since these subgenera are hard to characterize even 

 by experts, such keys have often led to more confusion than clearness, and 

 hence are abandoned here. The key used no doubt has its shortcomings 

 also, but it has been tested in my classes, and seems reasonably serviceable 

 .for the identification of the species as understood in this paper. 



The study of this genus has been carried on for several years in Michigan 

 under the most favorable conditions. The season of 1907 at Ann Arbor, 

 and the season of 1906 on the southern shore of Lake Superior, yielded 

 Russulas in great profusion. During my visit to Sweden in 1908, I had 

 similar good kick, both in the abundance of species and individuals belonging 

 to this genus, and in the opportunity to associate with Lars Romell* of Stock- 

 holm and M. Peltereau of Vendome, France, both of whom have written 

 papers on the Russulas of their respective countries. I am under obligations 

 to C. H. Peck for identification of specimens, and for critical advice, and to 

 a number of friends for favors mycological. 



The descriptions of the species given in the following pages, were made 

 from copious notes on fresh, living plants, and are not the result of guesses, 

 in this one respect at least it seems to me information actually important is 

 being offered in this paper. The descriptions, of course, are therefore local 

 and limited, and this fact is thoroughly appreciated; on the other hand 

 systematic mycology would be much more rapidly advanced if we had access 

 to a large number of good local accounts, than by the making of broad general- 

 izations on a few plants from widely separated localities. In all cases, except 

 where noted, the descriptions were obtained from Michigan plants, and are 

 intended primarily to provide the people of the state with a means of identifi- 

 cation for their own plants. The critical notes under each species have been 

 appended for a more special class of students, and are intended to help bring 

 order out of the chaos which exists with reference to the identity of American 

 and European species. As can be seen by a study of the notes and references 

 there is considerable disagreement among the European mycologists them- 

 selves. It would seem, however, that they have had enough time to 

 straighten out their own tangle, and it is time that we proceed to accomplish 

 something on this side of the water, without waiting for them to agree among 

 themselves. 



^l' KEY TO THE SPECIES. 



(Numbers refer to text.) 



(A) Gills unequal, alternately long and short, flesh thick to the margin of the pileus, which is at first 

 incurved and never has striations. {Compactae.) 

 'a) Flesh white, unchangeable. 



(b) Gills subdistant, edge sometimes tinged green. / 1. R. delica Fr. 



{ 1. R. chloroides Bres. 

 (bb) Gills close. 



(c) Pileus becoming "sooty-gray." 6. R. aduda (Pers.) Fr. 



(cc) Pileus whitish, becoming rusty-ochraceous or rusty stained. 



(d) Odor strong, alkaline: pileus very large, subviscid; gills with a faint pinkish 



tinge. 9. R. magnifica Pk. 



(dd) No odor; pileus dry; gills white, soon "tinged pale cinnamon." 



2. R. Irevipes Pk. 



*Dr. M. A. Lindblads Svampbok, bearbetad ax Lars Eomell, 19"2. 



