Lichen observations in bog areas of the Grossschlieren valley, Sarnen, canton of Obwalden (Central Switzerland). Following up earlier lichen surveys in the Glaubenberg-Fürstein Natural Forest Reser- ve in Central Switzerland (Cantons of Lucerne and Obwalden), we here report lichen observations in bog areas located further north-east in the Grossschlieren valley. Attention was focused on so-called key structures, which often proved to be sites of remarkable lichen species in the previously investigated areas. In a bog with abun- dant occurrence of reindeer lichens also the soil-inhabiting lichens were examined. Additionally, in a natural forest reserve, the old-growth forest lichens were the focus of the investigations. As a result, various interesting species are reported from the areas examined, including species considered to be relicts of a once more extended bog lichen vegetation.