PODOSPIIAERA 41 



sometimes nearly obsolete, sometimes well-developed, short, more 

 or less tortuous, pale brown, simple or irregularly branched ; ascus 

 oblong to subglobose, 55-70 x 44-50 «; spores 22-26 x 12-14 

 /i, crowded in the ascus. 



Hosts. — Pyrns Mains, P. Sicboldi. 



Distribution. — Europe : Germany, Austria-Hungary (Tyrol), 

 Russia (Tauria). Asia : Japan. North America : United States : 

 Vermont, Wisconsin, Mississippi (60), Iowa, Missouri (117), Kan- 

 sas (154). 



In its characteristic form this species, when in fruit, produces 

 matted patches on the young stems of the apple, occasionally 

 occurring on the petioles or very rarely scattered on the leaves. 

 The patches of densely compacted perithecia among the persistent 

 mycelium, from their long, more or less erect rigid appendages, 

 give a densely hirsute appearance to the infected stem. These 

 apical appendages are, however, apparently very deciduous. 



The present species was first described in 1888 as Sphaerotheca 

 leucotricha by Ellis and Everhart (117). Burrill (60), in 1892 

 changed the name to S. mali (Duby), identifying it with the Ery- 

 siphe mali of that author. Burrill remarked as follows : " This 

 exceedingly interesting species has not "been well separated from 

 Podosphaera oxyacanthae which occurs on the same host, and to 

 casual observation has much the same appearance. In our species 

 the tips of the large appendages are occasionally forked (once or 

 even slightly twice), which again may have been confusing. But 

 these vague stiff branches are totally unlike the dichotomous divi- 

 sions of Podosphaera, and otherwise the species are very distinct. 

 The tuft of short, interwoven, rudimentary appendages, like a dense 

 cluster of short roots, is a very characteristic mark." Duby's 

 Erysiphe mall Bot. Gall. 2 : 869, however, is not the present spe- 

 cies but is Phyllactinia corylea, as an examination of the type in 

 Duby's herbarium at the University of Strasburg showed. 



From the study of many examples of the present plant, in- 

 cluding authentic specimens kindly sent by Professor Ellis, I am 

 led to refer the fungus to the genus Podosphaera rather than to 

 Sphaerotheca. The apical appendages are quite different from 

 anything found in the genus Sphaerotheca, while similar in struc- 

 ture and insertion to those of Podosphaera oxyacanthae var. tri- 



