Marginal populations are those located at the extreme or periphery of a species' range. In the context of this paper, marginal populations refer to a geographical periphery rather than to possible ecological margins. A wide ranging species may be composed of several different varieties or ecotypes. Marginal populations of plants are of special interest to plant taxonomists, ecologists, ecological geneticists and biogeographers because they may exhibit different characteristics than more centrally located populations. This is likely because plants at the boundaries of their species' range may experience extreme ecological conditions beyond which they cannot survive.
Reinartz, J.A. and G.E. Reinartz. 1981. Vascular plants near the margins of their range in Cedarburg Bog. Part 1. Gymnosperms and Monocots. Field Station Bulletin 14(2): 1-13.