A Systematic Revision of the Carex Nardina Complex (Cyperaceae)

Abstract

The Carex nardina complex is a group of one to three species (C. nardina, C. hepburnii, C. stantonensis) and six taxa of unispicate sedges (Cyperaceae), the taxonomy of which has been controversial since the 1800s. As initial DNA phylogenies suggested that the complex was nested within Carex section Filifoliae and sister to C. elynoides, a species often confused with C. nardina and sympatric with it in the western North American Cordillera, analyses were conducted to determine whether C. hepburnii, C. stantonensis and other infraspecific taxa could be the result of hybridization. Morphometric and molecular analyses found no substantial evidence for hybridization and supported the recognition of no taxon beyond C. nardina. Consequently, this study concludes that the complex comprises a single variable species, Carex nardina, distributed throughout arctic North America south through the western Cordillera to New Mexico with a minor portion of its range in northeastern Russia, northwestern Scandinavia and Iceland.