THE FLORA OF SITKA, ALASKA 477 



THE FUNGUS FLORA. 



"Work on the fungus flora has been largely confined to para- 

 sitic forms or those appearing on particular hosts shortly after 

 the death of the plant. Of the groups to which little attention 

 has been paid, the Agaricacese should receive mention on ac- 

 count of their abundance in both species and individuals. Sev- 

 eral species arc gathered and used as food. 



During- the past two years, during which time the writer 

 has been at Sitka, a collection of nearly 300 numbers of fungi 

 has been made. In this collection imperfect forms and Pyre- 

 nomycetes greatly predominate. While many of the species are 

 known, there are so many unidentified forms in most orders and 

 families that it is deemed advisable, at this time, to consider 

 only two groups — the Erysiphacese and the Uredinales — leav- 

 ing the other groups until further identifications may be made, 

 when it is hoped to present the same in considerable detail. 



ERYSIPHACEjE. 



The Erysiphacea?, commonly called Powdery mildews, are not 

 so abundant as they are in many other localities. They were 

 collected on only about fifteen different host plants, whereas the 

 writer found them to occur on at least 186 hosts in the State 

 of Iowa, 4 and Salmon 5 enumerates a host index of much more 

 than 1,200 species. 



In this list, and also the one that follows, on the Uredinales, 

 the numbers in parentheses which follow the name of the host 

 plant refer to the collection number. 

 Sphaerotheca humuli (DC.) Burr. Hop Mildew. 



On Epilobium affine Bong. (72). On this host the mildew- 

 seems very destructive at times, and is quite widespread. 

 On Fragaria chiloensis (L.) Duchsne. What appears to be 

 the conidial stage of this mildew is troublesome in the 

 greenhouse on young plants which are hybrids of this 

 species. 

 On Fragwria platypetala Rydb. This species also is affected 



in the greenhouse. 

 On Ribes aurcum Pursh. (248). Only one slight infection 



observed on this cultivated species. 

 On Ribes bractcosum Dougl. (73 and 188). Not widespread 

 but sometimes quite severe on this native currant. Some 



