The reproductive biology of Magnolia grandiflora

The reproductive biology of Magnolia grandiflora was investigated at three localities in south Louisiana. Over the 3-4 day flowering period, the flowers of M. grandiflora exhibited changes in sex expression (protogyny), stigmatic receptivity (self-and cross-compatibility to self-incompatibility), UV reflectance (strong reflectance of the stigmas to strong reflectance of the androphore), and pollinator reward (a hexose-dominated stigmatic nectar to pollen). Although beetles were occasional floral visitors and carried pollen, bees (non-native Apis mellifera and indigenous Lasioglossum bruneri) were frequent floral visitors and were the only floral visitors whose behavior showed any correlation with the array of floral changes that occurred over the 3-4 day flowering period.