[Vol. 2 



696 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



The White Species of Polyporus — Those Watery and 



Fleshy-Tough when Fresh and with White 



Context and Spores 



This group of plants has probably been the source of more 

 trouble and exasperation to those collecting them than any 

 other group in the Polyporaceae. Collectors have sent them 

 to various mycologists for determination, and quite often no 

 two will agree on the name that should be applied to any one 

 form. 



The group of species with which we are here concerned has 

 been divided into two genera by Murrill, namely, the genus 

 Tyromyces and the genus Spongipellis. Since the characters 

 that separate the latter from the former genus are not always 

 well denned, it would seem better had they been united into 

 one genus. The group includes those species found only dur- 

 ing the summer and fall, growing on logs or on living trees, 

 and further characterized by being white or whitish through- 

 out, and having a more or less watery and soft fibrous con- 

 text. Some of the species have characteristic odors that will 

 usually aid in their identification. When dry the context of 

 some of these is soft and friable, sometimes more solid, and 

 sometimes differentiated into an upper soft portion and a 

 lower firm portion. We cannot include here all of the species 

 referred by Murrill to the two above-named genera, partly 

 because there has been no opportunity to study all of them and 

 partly because many of them are limited in their distribution 

 and are only infrequently found by collectors. Those that are 

 of common occurrence in the Ohio and the upper Mississippi 

 River valleys have been studied and the results here pre- 

 sented. The series thus limited includes the following species : 

 P. albellus Peck, P. caesius Schrad. ex Fries, P. chioneus Fries, 

 P. delectans Peck, P. fumidiceps Atk., P. galactinus Berk., P. 

 lacteus Fries, and P. spumeus Sow. ex Hornemann. These are 

 not all closely related and most of them are not difficult to 

 determine but they have been more or less confused in this 

 country, and their distinguishing characters are here pointed 

 out. 



