THE COMPARATIVE ECOLOGY OF FLOWERING

S ummary The major roles of flowering are in sexual reproduction and in fruit and seed production. Flowering competes with vegetative growth and vegetative reproduction for resources, and involves heavy resource costs which are often much greater than those required for seed production alone. Interactions between plants dependent upon flowering may be competitive or mutualistic. Theoretical models suggest that these interactions may often be of primary importance in determining whether different species or genotypes coexist, or displace or mutually exclude one another, and may thus be responsible for the heavy investment in flowering, but very few cases have been analyzed satisfactorily. The existence of simultaneously or sequentially flowering guilds of species with similar floral characteristics may be a consequence of mutualistic interactions. Flowering strategies and the range of possible interactions dependent upon flowering are potentially very diverse but are constrained by the physical and biotic environment, sometimes very severely.