Extract from Wikipedia article: Puccinia poarum,, the coltsfoot rust gall or meadow grass rust, is a plant pathogen. This fungal parasite forms a bright yellow gall, 1–2 cm across, on the underside of leaves of the coltsfoot (Tussilago farfara) and infects, but does not gall grasses of the family Poaceae.
Coltsfoot lower epidermis with rust (coltsfoot rust gall, Puccinia poarum) in Petiayarvi, north from Saint Petersburg. Russia, July 21, 2017 Shosseynaya ul., Petyayarvi, Leningradskaya oblast', Russia, 188732
Coltsfoot rust gall fungus, Puccinia poarum, in Sosnovka Park. Saint Petersburg, Russia, May 27, 2019 Unnamed Road, Sankt-Peterburg, Russia
Underside of a leaf with coltsfoot rust gall fungus, Puccinia poarum, in Sosnovka Park. Saint Petersburg, Russia, May 27, 2019 Unnamed Road, Sankt-Peterburg, Russia
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