Systematics of eriogonoideae s.s. (Polygonaceae)

Eriogonoideae s.s. (buckwheats and spineflowers, Polygonaceae) comprise morphologically diverse plants (ca. 325 species, 20 genera) distributed amphitropically in the New World. The lineage is hypothesized to have recently diversified mostly in arid habitats of the western U.S., where species richness and endemism are highest. Generic classification within Eriogonoideae s.s. has been unstable, mostly due to different morphological interpretations of the involucre. This dissertation addressed the systematics, character evolution, and adaptive diversification of Eriogonoideae s.s., and included: (1) phylogenetic estimation using multiple genes and optimality criteria, and a large taxon sample; (2) study of morphology to identify synapomorphies and examine character evolution; and (3) study of Latifolia, a subclade of Eriogonoideae s.s., employing morphological, genetic and ecological data for statistical correlation analyses to examine putative adaptive diversification. The findings of these studies have informed taxonomy, and shed light on the evolution of Eriogonoideae s.s.