XVI International Botanical Congess

Characters that correlate with major radiations of species are of particular interest in systematics. Developmental studies may suggest candidate genes whose modification resulted in characters now used to recognize large groups (often ranked as subfamilies or families). An example is provided by the panicoid grasses, which have been classically recognized by their paired flowers, one of which is hermaphrodite, the other staminate or sterile. Staminate flowers of all studied Panicoideae form via a pattern of controlled cell death in the gynoecium, this mechanism is apparently unique to the subfamily and suggests genes that might be involved in the origin of this group of approximately 3000 species. Major groups within the subfamily are recognized by their inflorescence form, and developmental studies suggest additional genes whose expression could be investigated.