Morphology and ultrastructure of uredospores of Melampsora larici-populina Kleb1

The morphology and infrastructure is compared for uredospores of Melampsora larici-populina Kleb., collected from the leaves of Populus nigra and P. trichocarpa. Though the spores differed in pigmentation it was not possible to show significant differences in their morphology and ultrastructure.