Abstract
Dryopteris fragrans has a global interrupted circumpolar distribution in the Northern Hemisphere, and the temperate forests of the Northeastern United States represent the southern periphery of its range. This species is globally secure, but rare in these forests. Genetic and phenotypic diversity within and among D. fragrans in the Northeastern US was investigated using ISSR-PCR and morphometrics. One population from Canada (Johansen Bay, Nunavut), where D. fragrans is more broadly distributed, was included to obtain an insight on central-peripheral relationships. The results indicated that genetic diversity was low within and higher among peripheral D. fragrans populations. Phenotypic diversity was high within and low among most peripheral populations. Genetic differentiation was considerable between the Canadian and peripheral populations, as 39 loci were found to be unique to each region. This study will contribute to the formulation of appropriate conservation and management strategies for D. fragrans in the Northeastern US.