Dryas octopetala
It is often assumed that an organism which currently has an Arctic–alpine distribution was, during colder periods of the Earth's history (such as during the Pleistocene glaciations), widespread across the area between the Arctic and the Alps. This is known from pollen records to be true for "Dryas octopetala", for instance. In other cases, the disjunct distribution may be the result of long-distance dispersal.