Darwin's legacy: the forms, function and sexual diversity of flowers

Abstract

Charles Darwin studied floral biology for over 40 years and wrote three major books on plant reproduction. These works have provided the conceptual foundation for understanding floral adaptations that promote cross-fertilization and the mechanisms responsible for evolutionary transitions in reproductive systems. Many of Darwin's insights, gained from careful observations and experiments on diverse angiosperm species, remain remarkably durable today and have stimulated much current research on floral function and the evolution of mating systems. Here I review Darwin's seminal contributions to reproductive biology and provide an overview of the current status of research on several of the main topics to which he devoted considerable effort, including the consequences to fitness of cross-versus self-fertilization, the evolution and function of stylar polymorphisms, the adaptive significance of heteranthery, the origins of dioecy and related gender polymorphisms, and the transition from animal pollination to wind pollination. Post-Darwinian perspectives on floral function now recognize the importance of pollen dispersal and male outcrossed siring success in shaping floral adaptation. This has helped to link work on pollination biology and mating systems, two subfields of reproductive biology that remained largely isolated during much of the twentieth century despite Darwin's efforts towards integration.

A New Genus and New Combinations in Australian Villarsia (Menyanthaceae)

“…Gynodioecy and dioecy also promote outcrossing, with the latter representing the most effective mechanism to avoid self-pollination ( Charlesworth and Charlesworth 1978 ). Furthermore, gynodioecy often constitutes a transitional step in the evolution of dioecy ( Barrett 2010 ). The existence of a similar 'gynodioecy pathway' to dioecy in Nymphoides is supported by the previously inferred sister relationship between N. cristata and N. cordata .…”

An angiosperm-wide analysis of the gynodioecy–dioecy pathway

“…The evolution from hermaphroditism to dioecy (separate sexes) is considered one of the most important evolutionary transitions in the reproductive history of angiosperms (Barrett, 2010). Although relatively rare (approx.…”

Sex-Specific Flowering Patterns and Demography of the Understorey Rain Forest Tree Iryanthera Hostmannii (Myristicaceae)

“…Inter-sexual variation in plant form and function has been a fertile topic of investigation since Darwin [54]. Dioecious species provide a natural experiment with which to study how high (in females) vs. low (in males) allocation to reproduction affects life history.…”