UREDINALES 



89 



PUCCINIOPSIS : producing aecidia and teleutospores. 



BRACHYPUCCINIA : producing spermogones, uredospores and 

 teleutospores. 



HEMIPUCCINIA : producing uredospores and teleutospores. 



MICROPUCCINIA : producing only teleutospores which remain 

 over winter before germinating. 



LEPTOPUCCINIA : producing only teleutospores which germinate 

 soon after maturity. 



It is customary for brevity to designate the aecidia as I, the 

 uredo as II, and the teleutospore as III. 



The rusts are grouped in four families of which only two * are 

 known from the United States. These may be separated as 

 follows : 



Teleutospores in flattened or cushion-like masses, or loose in the tissues of 

 their host ; stemless. Fam. I. Melampsoraceae. 



Teleutospores stalked (rarely the stalk is very short), separate or united in 

 sori of a definite form. Fam. 2. Pucciniaceae. 



Family I. Melampsoraceae. 



This family has the following genera in the United States : 



1. Teleutospores formed in rows by successive division of the sporophore, 



bursting through the tissues of their host. 2. 



Teleutospores not formed in rows ; sori remaining covered by the epider- 

 mis or cuticle of their host. 3. 



2. Teleutospores formed in cushions. CHRYSOMYXA. 

 Teleutospores formed in columnar or filiform masses. CRONARTIUM. 



3. Teleutospores formed in waxy masses, dividing into four cells of which 



the uppermost bear sterigmata. COLEOSPORIUM. 



Teleutospores germinating with normal promycelium. 4. 



4. Teleutospores one-celled (rarely 2-celled with one cell above the other), 



uniting laterally in an irregular crust. MELAMPSORA. 



Teleutospores mostly 2-4-celled, the cells side by side. 5. 



5. Teleutospores united in a thick crust formed either in the epidermal 



cells or immediately under them. 6. 



Teleutospores single or in loosely united groups, buried in the paren- 

 chyma of their host ; (parasitic on ferns. ) UREDINOPSIS. 



* Species of the genus Endophyllum which produce teleutospores 

 within a pseudoperidium will be found, doubtless, on some of our fleshy 

 plants. The three known European species grow on Sediim, Sempervivum, 

 and like plants ; they form the type of a distinct family. 



