Aug. 27, 191 7 Puccinia graminis on Cereals and Grasses 



433 



The following biologic forms are discussed in the paper : Puccinia gram- 

 inis tritici Erikss. and Henn. ; P. graminis iritici compacii, form. nov. ; 

 P. graminis secalis Erikss. and Henn.; P. graminis avenae Erikss. and 

 Henn. ; P. graminis phleipratensis, comb. nov. = (P. phleipratensis Erikss. 

 and Henn.); P. graminis agrostis Erikss. 



KHY To TABLES I-XXVII 



In Tables I to XXVII "Place" refers to the place of collection, and 

 "Date," to the date on which inoculations were made. The plants 

 inoculated are listed in the same line with place and date and the results 

 are given in the form of a fraction. The denominator indicates the 

 number of leaves inoculated and the numerator the number which 

 developed uredinia. The figures after the semicolon give the number 

 of leaves which were distinctly flecked. The degree of infection is not 

 indicated in the tables, but it is given in the discussions following the 

 tables. 



Table I.^Results of inoculations with uredinios pores from Agropyron caninum (L.) 



Beauv. 



P. graminis tritici compacii is a form recently described by the writers 

 (29) as differing from other biologic forms in its action on most common 

 wheats (Triiicum vulgare Vill.). There seems to be no valid reason for 

 not considering the timothy rust as a biologic form of P. graminis. 

 Further discussion of biologic forms is given after Tables XXVIII to 

 XXXIII. 



Reference is sometimes made to strains of a biologic form. This 

 means merely rust with a certain history and does not necessarily indi- 

 cate that the so-called strain is different from the typical rust of the 

 biologic form in question. For instance, if P. graminis tritici had been 

 collected on Agropyron tenerum and Hordeum juhatum and the rust 

 from each cultured separately in the greenhouse for a number of genera- 

 tions, the two would be known as strains. 



