Abstract
The problem of species concepts and delimitation in the heteroecious rusts is discussed. It is illustrated by Puccinia karelica, which is known in typical form from Europe, southern Alaska, coastal British Columbia, and apparently Kamchatka and Saghalien. A distinct population in eastern Canada and adjacent United States is named ssp. laurentina ssp. nov. P. karelica is compared with closely related species and its probable mode of evolution is discussed.

This publication has 3 references indexed in Scilit: