XVI International Botanical Congess
Carex sect. Deweyanae is a group of mostly woodland sedges of eastern Asia and much of North America. Phylogeny of this and related sections had been unstudied. Also, circumscription of the section and several taxa in it are controversial. Difficulty in defining the section stems from the existence of few distinctive morphologic features for it and the existence of species (notably C. laeviculmis) somewhat intermediate between sect. Deweyanae and sect. Stellulatae. Preliminary results of phylogenetic analyses reveal that C. laeviculmis belongs to sect. Stellulatae due to its spreading perigynia, an apomorphy of that section. Section Deweyanae is apparently monophyletic, based on the apomorphy of perigynia with length/width ratios relatively high (2.5-6.6). The section appears to contain 6 species: C. bolanderi, C. bromoides, C. deweyana, C. leptopoda, C. senanensis, and 1 undescribed species.