Nectar dynamics and reproductive biology of Passiflora actinia Hook. (Passifloraceae) in Araucaria Forest

Abstract

ABSTRACT Nectar production has an important role in pollinator attraction and successful fruit production in many self-incompatible angiosperm groups. The reproductive biology of Passiflora actinia was studied here and related to nectar dynamics. Passiflora actinia presented a temporal segregation of male and female functions at the beginning of anthesis. Due to the movements of floral verticils, the anthers were positioned in a way that favors pollination two hours before the stigmas reached the same position. The nectary consisted of an epidermis with stomata and a parenchyma rich in starch, which was hydrolyzed during anthesis. The nectary organization is probably associated with the continuous production of nectar during anthesis as well as with the high mean nectar concentration. Hand pollination tests indicated that Passiflora actinia is obligately xenogamous, depending on large bees for pollination, specifically the carpenter bee Xylocopa augusti. The continuous production of nectar may increase the number of bee visits, thus favoring pollen flow.