Flower development: initiation, differentiation, and diversification.

Flowering is one of the most intensively studied processes in plant development. Despite the wide diversity in floral forms, flowers have a simple stereotypical architecture. Flowers develop from florally determined meristems. These small populations of cells proliferate to form the floral organs, including the sterile outer organs, the sepals and petals, and the inner reproductive organs, the stamens and carpels. In the past decade, analyses of key flowering genes have been carried out primarily in Arabidopsis and have provided a foundation for understanding the underlying molecular genetic mechanisms controlling different aspects of floral development. Such studies have illuminated the transcriptional cascades responsible for the regulation of these key genes, as well as how these genes effect their functions. In turn, these studies have resulted in the refinement of the original ideas of how flowers develop and have indicated the gaps in our knowledge that need to be addressed.