An enormous diversity of size, shape, and complexity exists among the flowers of the quarter-million species of angiosperms. Flower size varies over a thousandfold, with Rafflesia (Rafflesiaceae) flowers as large as 1 meter in diameter dwarfing the minuscule flowers of Wolffia (Lemnaceae), which measure less than 1 millimeter across. The number of floral organs also varies, with the complex flowers of the Tambourissa (Monimiaceae) species having more than one thousand organs while the simple flowers of the Chloranthaceae may consist of just a few. The coevolution of angiosperms with their animal pollinators is a driving force in the generation of flower diversity. The end product of pollination is the formation of a viable seed, therefore ensuring that the species will be perpetuated. Exclusive pollinator-flower relationships ensure that pollen will not be wasted by delivery to flowers of a different species.

Definition and Flower Parts

Despite the enormous diversity in the...