REPURPOSED GENES. “Thus, it seems reasonable to conclude that: (1) orthologs of most floral genes existed long before their specific roles in flowering were established; (2) novel gene lineages first appeared with the origin of the angiosperms and probably contributed to the origin of the flower; and (3) after a functional flower evolved, genetic innovations continued as new genes originated and/or were recruited into floral genetic programs.”
http://www.genetics.org/content/202/4/1255