Biosystematics of the Genus Heuchera (Saxifragaceae)

The plant genus Heuchera (Saxifragaceae) consists of more than 40 species of plants largely specific to rock outcrops in montane regions, known for its difficult species delimitation attributable to hybridization and polyploidy. Presented herein are taxonomic and phylogenetic studies intended to clarify the evolution of this plant genus and to elucidate species boundaries in problematic species complexes. A study on whole-genus phylogenetic relationships using six nuclear DNA sequence loci and 39 morpological characters constitutes the first chapter. Following this is a study on species delimitation in the Heuchera parviflora complex using molecular and morphological data. Revisionary studies are afterwards presented which treat taxa occuring in Mexico (heretofore the most problematic of all Heuchera species), treated in two separate chapters to reflect two apparently unrelated circles of affinity among the Mexican taxa, and finally a study of southwestern U.S. species of section Heuchera which are also poorly known. This work is concluded with studies using new sequencing technologies to provide a genomic view of Heuchera: a new method for sequence capture in recently diverged complexes is followed by a phylogenomic study that improves upon the work presented in the first chapter.