Cronartium flaccidum f.sp. flaccidum on Pinus sylvestris: a. Stem of young tree with numerous aecia; b. Slightly swollen Pinus twig with aecia; c. Mature aecium with rupturing peridium; d. Peridium cells in longitudinal section; e. Aeciospores in optical section and surface view; note the reticulate cracks in the smooth part of the spore wall; f. Aeciospores in SEM showing the broad, nearly smooth part of the spore wall with the fine network of cracks (arrows) and the annulate wall ornaments; (a by Julia Kruse; b, c from Dietel 1928: 42, with permission from Duncker & Humblot GmbH; d, e from Klebahn 1914: 722; f from Zwetko and Blanz 2018: 277).

 
 
  Part of: Zwetko P, Scheuer C, Krisai-Greilhuber I, Blanz P (2024) Rust fungi of Austria 1 (excluding Puccinia s.l. and Uromyces): Melampsoraceae and related families, Gymnosporangiaceae, Ochropsoraceae, Phragmidiaceae, Tranzscheliaceae, and Genera incertae sedis. Biosystematics and Ecology 3: e123592. https://doi.org/10.1553/biosystecol.3.e123592