Melampsora allii-fragilis on Salix fragilis: a, b. Urediniospores with (almost) smooth apex; spines increasing in size and density towards the base; spore wall sometimes thinner at certain spots; c, d. Telium on the upper side of the leaf in vertical section, teliospores arranged in subcuticular crusts, spore wall evenly thick; e. Telium on the lower side of the leaf showing shorter spores; (a, c, d, e from Klebahn 1914: 782; b by Paul Blanz).