Chemotaxonomy of the genus Carex (Cyperaceae)

Abstract

The major categories of chemosystematic comparisons that were used successfully or are of potential use in Carex include flavonoid analysis, enzyme electrophoresis, and chloroplast DNA mapping and sequencing. The flavonoid work consists mostly of broad scale comparisons of aglycone distributions in a number of sedge genera to include some members of Carex. These comparisons proved to be of limited use in understanding phylogenetic relationships within the genus Carex. However, detailed flavonoid analyses of sections Laxiflorae and Acrocystis demonstrated the utility of flavonoid surveys in Carex at infrasectional levels and possibly at intersectional levels. Enzyme electrophoretic data were used to determine whether the morphological variability present in a species complex is the result of hybridization, phenotypic plasticity, or recent divergence. The C. crinita complex is an example in which intermediate forms are probably not the result of hybridization. Conversely, allozyme data for section Sylvaticae indicate that some of the taxa in this section are of hybrid origin. One of the most promising developments in systematic studies was the use of chloroplast DNA analysis. It was demonstrated in a number of plant groups that restriction endonuclease and sequence comparisons of chloroplast DNAs can be used to construct phylogenetic trees that have homoplasy levels much lower than those constructed from phenotypic characters.