The Diversification of Flowering Plants

Abstract

Abstract In this chapter, we provide an overview of the phylogeny of flowering plants, with special emphasis on the root and major clades of the angiosperms, and patterns of radiation in the evolutionary history of angiosperms. Given the size of the angiosperm clade, we will not examine relationships within major clades in any detail; instead, we refer the reader to publications that focus on those clades or grades[e.g., basal angiosperms (Zanis et al. 2002), monocots (Chase et al. 2000), early-diverging eudicots (Hoot et al. 1999), asterids (Albach et al. 2001, Bremer et al. 2002)]. After this overview, we use the phylogeny to examine patterns of evolution in three important features of flowering plants: double fertilization and endosperm formation, closed carpels, and perianth structure and organization. The flowering plants are one of five clades of extant seed plants, and they are by far the largest, most diverse, and most important ecologically of all living embryophytes (land plants). There are at least 260,000 (Takhtajan 1997) species of flowering plants (i.e., five to six times the number of living species of vertebrates), classified in approximately 450 families (e.g., 453, as listed in Angiosperm Phylogeny Group II 2003).