169 



branches may be outlined as follows : A few small branches may 

 be seen to rise from the bases of the larger ones in almost any 

 mature shrub. When the older branches may be said to reach 

 a state of senescence, by reason of overflowering, the suckers are 

 noticeably abundant and relatively large, and finally, by the time 

 the twigs of the parent branch are dead, they have assumed 

 its form, have taken on its functions and have gradually replaced 

 it. Through the vegetative rejuvenescence the rhododendron 

 as a plant normally does not die, and it therefore may be consid- 

 ered, as Muir looks upon the big tree, as practically immortal. 



A KEY TO THE NORTH AMERICAN SPECIES OF 

 CORTINARIUS. — I 



By F. S. Earle 



The genus Cortinarius is one of the largest and most interest- 

 ing among the mushrooms, many of the species being of con- 

 siderable size and very attractive in coloring. As a rule they 

 are found during late summer and fall, many of them occurring 

 after the weather has become quite cool. Many of the species 

 are edible and so far as known none of them are dangerously 

 poisonous. 



The sections and subgenera in Cortinarius are for the most 

 part quite well marked and the study of the genus is made diffi- 

 cult by the great number of species and our limited knowledge 

 of them rather than by any lack of good specific characters. In 

 this genus the study of the earlier stages as well as of the fully 

 developed plant is unusually important. The color of the young 

 lamellae in particular should always be noted. 



It should be borne in mind, as was stated at the beginning of 

 this series of papers, that these keys are based on the existing 

 literature only, and not on a study of the plants themselves. 

 They are intended solely as an aid to the beginning of the serious 

 study of these interesting plants and not to express final con- 

 victions in regard to their relationships. 



