MICHIGAN ACADEMY OP SCIENCE. 59 



The Russulas are almost all Edible after careful cooking, as even the 

 peppery forms then lose their sharp taste. Because of the uncertainty of 

 identifications several species are still on the doubtful list, although Mellvaine 

 claims to have eaten even the R. emetica of evil fame. Certain it is that all 

 the mild forms are perfectly safe when fresh, young and clean. 



The Distribution of the different species depends apparently on two 

 factors ; the nature of the substratum — including soil and forest surroundings, 

 and the climate. Many species are limited to the coniferous regions of the 

 northern part of the state, while others are found only in the oak- openings 

 of southern Michigan. Some species are apparently symbiotic and form 

 mycorhiza on the roots of forest trees. Some prefer sandy soil in woods, 

 while others are usually found in open places pushing through hard clay 

 soil in roads, etc. We have at present entirely too few data on the life history 

 of individual Russulas to say much about their relationship to their surround- 



ings 



As has often been observed by collectors, * the Russulas are most abundant 

 in middle summer. If the weather be favorable, i. e. if moisture and warmth 

 have been supplied at the proper time and in proj.er seciuence, Russulas 

 appear in Michigan in greatest profusion during July and the first half of 

 August; after that time they are comparatively few and scattered. In the 

 northern peninsula they appear as a rule somewhat later, but this depends 

 again on weather conditions. A cool or dry early summer is likely to delay 

 the first crop, but does not seem to affect the later limit of their appearance. 

 The result is that there is a sudden and luxuriant fruiting of all forms during 

 a shorter period. In order to throw some light on their distribution through- 

 out the season, a table has been prepared from data collected at Ann Arbor, 

 in what may be considered a favorable year for Russulas. Trips were made 

 throughout the whole summer, averaging every other day except during a 

 period of three weeks of dry weather. The region covered was that of Wash- 

 tenaw county, and the time extended from July 8, to November 1. All the 

 dates on Avhich Russulas were found have been put down, and the species 

 are arranged in the order of their abundance. The crosses show that one 

 or more Russulas of a certain species were collected on a certain day. The 

 X 'marki means that they were very abundant on the day in question, 

 while the number one placed with the cross indicates that only one specimen 

 was found. Unfortuately there is no record in a great many cases, but where 

 they were found daily several specimens were usually collected. 



*Denniston, 1. c. 



