IMPORTANT SPECIES OF RUSTS 33S 



Physiologic forms have been demonstrated to exist among 

 other varieties of P. graminis and among other cereal rusts. 

 Knowledge of these matters requires perusal of the reports of the 

 extensive researches by Stakman and his associates. 



Classification of Uredinales 



There are two outstanding extensive monographic treatises 

 dealing with classification of the rusts: that by Arthur (1907- 

 1931), published in The North Ajiierican Flora; and Monographia 

 Uredinanmi, a four-volume series by the Svdows (1904-1924). 

 The Sydows' first volume is devoted to Puccinia, the second to 

 Uromyces, the third to all other genera, and the fourth to im- 

 perfect, cycled species. Other less comprehensive but very use- 

 ful taxonomic w^orks include those by Arthur (1934), Cunning- 

 ham (1931), Eriksson and Hennings' (1896), Faull (1932, 1934, 

 1938), Grove (1913), Kamei (1940), Kern (1911), Klebahn 

 (1904), Long (1903), and Ale Alpine (1906). 



The Sydows (1904-1924) separate the rusts into 3 families as 

 follows: 



1. Promycellum external 2 



2. Teliospores free, loosely fascicled, fused into a compound head, 

 or in chains, but never compacted laterally into crusts; usually 

 pedicellate Pucciniaceae 



2. Teliospores fused laterally to form a crust, or in columns, rarely 

 occurring singly in the host tissue; not stalked Alelampsoraceae 



1. Promycelium internal, teliospores fused laterally, forming waxy 

 closely adherent crusts Coleosporiaceae 



Arthur (1907-1931) employed essentially the same charac- 

 teristics in his familial separations, but in his Manual of the Rusts 

 in the United States and Canada only 2 families, the Alelamp- 

 soraceae and the Pucciniaceae, are recognized. The Alelamp- 

 soraceae are divided into 4 tribes, Puccinastreae, Cronartieae, 

 Alelampsoreae, and Phakosporeae; and the Pucciniaceae into 3 

 tribes, Ravenelieae, Phragmidieae, and Aecidieae. 



Important Species of Rusts 



The rusts are of great economic importance because of the 

 losses that they cause from their attacks, especially on cereals but 



