Melampsoridium hiratsukanum on Alnus incana: a. Uredinia hypophyllous, yellow-orange, but colour soon fading; b. Uredinium in vertical section; ostiolar cells forming a collar of long spines (arrow); c. Urediniospores; d. A small telium in vertical section; (a by Richard Tafner, with permission; b–d from Riegler-Hager et al. 2003: 137, with permission from the author, modified).