Variation in the Festuca brachyphylla (Poaceae) complex in Svalbard, elucidated by chromosome numbers and isozymes

Contrasting with former taxonomic treatments, chromosome numbers and isozym e data support the delimitation of the seminiferous representatives of the Festuca brachyphylla complex in Svalbard into four species: F baffinensis, F brachyphylla, R hyperborea and F edlundiae. Unique enzyme markers were fo und for all species. Festuca brachyphylla proved hexaploid, and the others, tetraploid. The chromosome numbers of F hyperborea and F brachyphylla (as circumscribed at present) are new to Svalbard. Festuca baffinensis is the m ost distinct species within the complex, probably representing a separate e volutionary lineage. The three other species seem closely related, showing mutually equidistant relationships. Some deviating plants found on disturbe d ground might represent hybrid derivatives or an introduced foreign strain of the elsewhere variable F brachyphylla. Materials of diploid F ovina fro m northern Fermoscandia was enzymatically closely related to the F brachyph ylla complex in Svalbard. Festuca brachyphylla, F edlundiae, and R hyperbor ea all had a stronger affinity to F ovina than to F baffinensis, indicating that the F brachyphylla complex is an artificial taxonomic group. There ar e reasons to believe that the origin of the polyploid taxa of the F brachyp hylla complex can be traced to diploid species of the R brachyphylla and F ovina complexes. (C) 2001 The Linnean Society of London.