Genetic variation and gene flow is examined for Dicranum elongatum on the beach ridge system along the Hudson Bay Lowlands in Wapusk National Park in Manitoba, Canada. Samples were collected from 10 quadrats from each of 14 transects on the beach ridge crests and in the low-lying troughs between beach ridges. Seven interspersed simple sequence repeat (ISSR) markers produced 34 polymorphic loci in 37 samples of Dicranum elongatum. AMOVA showed evidence for population subdivision with 87% of the variation occurring within populations, but pairwise comparisons showed evidence for low levels of gene flow. Since sporophytes were not present in the coastal populations but are produced by plants further inland, the genetic variation in the coastal populations may be maintained by wind blown spores from sexually reproducing inland populations.