NORTH AMKRICAX l'.\ R A S lilC EXOASeK.E. jq^ 



cies considerable variations frcjni the typical form and size of 

 the asci and stalk-cell, as well as divers spore measurements. 

 }3ut these phenomena which might be occasioned by climatic 

 influences upon the hosts, througii them affecting- the nutri- 

 tion and development of the fungus, seem not suflicient to 

 warrant the splitting up into new species; still it is not improb- 

 able that a more intimate acquaintance with the conditions of 

 the hosts occasioned b\' the presence of the' parasities and a 

 closer study of the life-history of the latter may justify an 

 increase of species 



ExoAscus PURPURASCENS {E///S ct" EvcrJiart \ Sadcbcrk. 

 Plate II. Fig. I. 



Bibl. and Syn. : 



Ji.xoasciis defonuaiis. var. Farlow '83. 



Farlow '85. 



Aicoiuxccs dcfoniicms. var. piirpiirasccns Ellis & E\erharl 



'B7.' 

 Tai)hrina piirpurasccns Robinson '87. 



Ellis 89. 

 Sadebeck 'yo. 

 Seviiioiir cS: Earle '92. 



Exoasctis ■pnrpnrasccm Saccardo '89. 



Exoas^cif} piirpurascois [ Ellis & Everhart ) Sadebeck "93. 



This fungus has so far only been definitely reported as 

 occurring in America and appearing upon the leaves of Rhus 

 copaUi)ia. the dwarf sumach. It has been observed in Mas- 

 sachusetts, New Jersey and Connecticut. The macroscopic 

 appearance of the leaves is characteristic; what are at first 

 round purple spots flow together irregularly until the entire 

 upper surface is covered and wrinkled, when the leaves hang 

 loosely down. The wrinkles are caused b}- the s\^ elling up 

 of the softer parts of the leaf-tissue between the nerves, the 

 swollen parts becoming convex above and concave below. 

 The mvcelium is perennial in the infected branches and from 



