The organisms that inhabit the lakes of the Tatra Mountains must be adapted to the extreme conditions that are generally characterised by very low temperatures, a short ice-free growing season and a lack of nutrients. The lower-lying lakes show a greater degree of diversity, whereas in the high mountain environment there are significantly fewer species. If higher plant species occur here at all, they do so in communities that are simple in structure and very species-poor. One of the rarest species of vascular plants that can be found in the lakes of the Tatras is the narrowleaf bur-reed...