PREFACE 
te is now twenty-four years since the publication of Plowright’s 
“Monograph of the Uredinez and Ustilaginee,” and during 
that long period very great progress has been made in elucidating 
the biology of the former group. To Plowright will ever belong 
the honour of being one of the pioneers in this important work, 
especially in that branch which is the most fascinating and 
has the greatest number of secrets to unfold—viz. Hetercecism. 
But since his time numerous investigators have followed in his 
footsteps, while others have taken new ground and largely 
increased our knowledge, so that the picture which he presented 
of the biology and classification of the Rusts has now become, 
in certain directions, very incomplete and misleading. 
The descriptions in the present volume are naturally based 
upon those in the “ Monographia Uredinearum ” of the brothers 
Sydow, so far as that monumental work has been published. 
Those of all the species of which British specimens could be 
procured have been carefully revised, and there is hardly one 
of them that has not been added to or amended. Fischer’s 
“Uredineen der Schweiz,” and McAlpine’s “ Rusts of Australia” 
have also been found extremely useful. No attempt has been 
made to give a full synonymy, but merely so much as was 
required to show the origin and authority of the name used, 
and to include all the references to the various species contained 
in the works consulted, especially those of Cooke and Plowright. 
Dates have been added occasionally, but only for special reasons 
or if the nomenclature adopted differs from that in the 
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