Life Cycle Plasticity in and in the Arctic and the Temperate Zone.

ceae Jülich is one of the cold-adapted fungal families in basidiomycetes. The representative genera, (Pers.) Fr. and Fr., are distinguished by the discontinuity between stems and hymenia in the former and the continuity in the latter (Fries 1821). This taxonomic criterion is ambiguous, and consequently, the view of Karsten (1882) has been widely accepted: develops basidiomata from sclerotia, while basidiomata develop directly from substrata in . However, Corner (1970) observed basidiomata of S. Imai developing from sclerotia in Hokkaido, Japan. We later recognized that basidiomata also emerged directly from substrates on the ground in Hokkaido. An aberrant form of H. Ekstr. was found in Upernavik, West Greenland. This specimen had a stem-like structure on a Poaceae plant, and sclerotia developed on its tip. Similar phenomena were found in other species in Japan. In this study, we aimed to elucidate the life cycle plasticity in the genera and through the interactions between their ecophysiological potential and environmental conditions in their localities. We collected and prepared strains of the above fungi from sclerotia or basidiomata, and we elucidated the taxonomical relationship and determined the physiological characteristics of our strains. Our findings imply that both and have the potential to produce sclerotia as well as the capacity for mycelial growth at ambient air temperatures in each locality where samples were collected. These findings suggest that spp. develope basidiomata not only from the sclerotia dispersed by the basidiospores but also from mycelia generated by the spore germination, which formed basidiomata multiple times, depending on their growth environments.