Ascomycetes on Pogonatum urnigerum (Musci)
A representative number of personal collections and herbarium specimens of Pogonatum urnigerum (Polytrichaceae, Musci) from many parts of its essentially holarctic distribution area were analysed for the presence of ascomycetes. The following species were noted on the gametophytic plants: Bryochiton perpusillus, Bryorella cryptocarpa, Dawsomyces sp., Epibryon bryophilum, E. casaresii, E. interlamellare and E. pogonati-urnigeri. By far the most frequent species was E. pogonati-urnigeri, growing immersed between the photosynthetic leaf lamellae. It is almost universally present including isolated host populations in Africa and Asia; it is unusual in having varying ascospore sizes. All other species only occur sporadically. Remarkably, neither discomycetes nor anamorphic fungi were detected. All P. urnigerum-inhabiting species are known to infect additional Polytrichaceae. The few ascomycetes observed on further Pogonatum species are also mentioned.