Model Species to Investigate the Origin of Flowers

The angiosperms, or flowering plants, arose at least 135 million years ago (Ma) and rapidly diversified to form over 300,000 species alive today. This group appears, however, to have separated from its closest living relatives, the extant gymnosperms, much earlier: over 300 Ma. Representatives of basally-diverging angiosperm lineages are of key importance to studies aimed at reconstructing the most recent common ancestor of living angiosperms, including its morphological, anatomical, eco-physiological and molecular aspects. Furthermore, evo-devo comparisons of angiosperms with living gymnosperms may help to determine how the many novel aspects of angiosperms, including those of the flower, first came about. This chapter reviews literature on the origin of angiosperms and focusses on basally-diverging angiosperms and gymnosperms that show advantages as potential experimental models, reviewing information and protocols for the use of these species in an evo-devo context. The final section suggests a means by which data from living and fossil groups could be integrated to better elucidate evolutionary events that took place on the long stem-lineage that apparently preceded the radiation of living angiosperms.