vi PREFACE 



" Monographia," where a complete synonymy, with dates, lies 

 at the disposal of those who are i 1 1 > < t< -i . •« I in thai matter. 



A plan has been adopted, in a few cases, of grouping 

 some forms thai are closely allied under a common name; 

 see Puccinia dispersa and /'. sessilis. With more knowledge 

 (or more courage) this process might have been carried much 

 farther, and it is hdicved that in this device will be found the 

 first line of defence of sane systematists against, the excess ive 

 multiplication of "species" by "biological" nomenclators. It 

 cannot be justifiable to use the same word in the same branch 

 of science to denote two widely diverse grades of evolution. 

 Physiological, unaccompanied by morphological, distinctions 

 should never be allowed to constitute a difference of species, 

 unless it be as a temporary measure in cases which have not 

 been investigated. 



In selecting the name for each species, the principle of 

 priority has been followed, subject to two conditions — (1) names 

 given to varieties need not be adopted (International Rules, 

 1905, Art. 49), and (2) names given to imperfect states are 

 not to be preferred, but the earliest name given to the perfect 

 (in this case, the teleutospore) stage (Brussels Congress, 1910); 

 sometimes, however, the name Uredo may have included the 

 perfect stage, as in some species of Uromyces (U. Scirpi, etc.). 



Since secidiospores are almost always " rounded-polygonal," 

 their shape is not mentioned unless it deviates from this form. 

 In the systematic part, all the spores are drawn to the same 

 magnification (600 times), except where indication to the 

 contrary is given. The drawings are all original and from 

 British specimens, unless a different source is stated. When 

 several similar spores are outlined, the surface-sculpture is not 

 always indicated upon every one of them. 



My thanks are especially due to Professor G. S. West, by 

 whose advice this work was undertaken and by whose assistance 

 it has been chiefly carried through. The 'Plowright' Herbarium 

 of Fungi, which is in the possession of the University, has been 



