KEY TO THE COMMONER NORTH AMERICAN GENERA OF FAMILY PUCCINIACEAE 425 



Promycelium not septate, the four to many sporidia at its blunt apex. Telio- 



spores mostly arising as lateral outgrowths from hyphal cells or intercalarly. 



Sporidia expelled from the promycelium. Family Tilletiaceae 



Promycelium lacking, but the teliospores bud directly to form four sporidia 



which form thick, dark walls. Teliospores in vertical rows in compact sori. 



Parasites in leaves of palms. Sporidia not expelled violently. 



Family Graphiolaceae 



Key to the Commoner North American 

 Genera of Family Melampsoraceae 



(Based upon Arthur, 1934) 



Teliospores single or united laterally into groups of two or more. 

 Telia in ferns (Polypodiaceae and Osmundaceae), aecia in Abies. 

 Teliospores subepidermal. Uredinopsis 



Teliospores in the epidermal cells. 



Aeciospores and urediospores colorless. Milesia 



Aeciospores and urediospores with yellow contents. 



Hyalopsora 

 Telia in Anthophyta (Angiospermae) . 



Teliospores with brown walls. Pucciniastrum 



Teliospores with colorless walls. 



Peridium of uredium delicate, with a central pore. 



Melampsorella 

 Peridium of uredium firm, with long-pointed ostiolar cells. 



Melampsoridium 

 Teliospores united laterally into subcuticular or subepidermal crusts. 

 Promycelium external. 



Teliospore walls colored. Melampsora 



Tehospore walls colorless. Aplospora 



Promycelium within the teliospore. Coleosporium 



Teliospores in chains which are united laterally into long columns emerging 

 through the epidermis. Urediospores borne singly on stalks. 



Cronartium 

 TeUospores in chains which are not united laterally and not emerging as a column. 



Urediospores in chains. Chrysomyxa 



Teliospores united laterally into crusts of two or more layers, mainly tropical. 

 Life histories not well known. Bubakia, PhysopeUa, 



Cerotelium, etc. 



Key to the Commoner North American Genera of Family Pucciniaceae 



Teliospores borne singly. 



Teliospores colorless; aecia peridermioid; autoecious. Mainsia 



Teliospores colored. 



TeUospores flattened vertically; aecia uredioid; autoecious. 



Pileolaria 

 Teliospores spherical or short ellipsoidal, aecia uredioid, autoecious; spermo- 



gonia subcuticular.' Trachyspora 



TeUospores spherical or short ellipsoidal, with thickened apex; aecia cupulate 

 (rarely uredioid); autoecious or heteroecious; spermogonia sub- 

 epidermal. Uromyces 



