Evolution of Aquatic Angiosperm Reproductive Systems

vironments and became aquatic. Aquatic plants are species that perpetuate their life cycle in still or flowing water, or on inundated or noninundated hydric soils. Aquatic angiosperms inhabit oceans, lakes, rivers, and wetlands. The transition to an aquatic life has been achieved by only 2% of the approximately 350,000 angiosperm species (Cook 1990). Nonetheless, the evolutionary invasion of aquatic environments by terrestrial angiosperms is estimated to represent 50-100 independent events (Cook 1990). Although aquatic plants are typically discussed as a unified biological group, the ways that species have evolved to life in the aquatic milieu are as diverse as the different