Melampsora pulcherrima is a Mediterranean plant pathogen. It is a rust that infects Mercurialis annua, causing galls, pycnia, and aecia over leaves and stem in winter, seen as a golden yellow swelling over several centimeters, as well as Populus alba, causing uredia and telia on leaves from spring until autumn.
References
External links in Penetration and earlycolonization in basidiospore-derived infection of Melampsora pulcherrima (Bub.)Maire on Mercurialis annua L.