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

Abstract

Nectar production has an important role in pollinator attraction and successful fruit production in many selfincompatible 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.

Nocturnal and crepuscular pollination of Passiflora morifolia (Passifloraceae): breeding system, floral biology and pollinators

“…Plebeia droryana contributes to the pollination of the small-sized flowers of P. suberosa, but it was considered a nectar thief in P. miersii (Koschnitzke & Sazima, 1997). For other Passiflora species, with large flowers and great spatial separation between the reproductive structures and the corona (where they land when they take nectar), visitation by these bees does not always seem to have positive effects, as in P. actinia, in which Plebeia remota was considered a nectar thief (Varassin et al, 2018). Trigona spinipes was also considered an occasional pollinator of P. morifolia because, depending on its movement in the flowers, it touched the anthers and stigmas with its thorax and head and carried pollen.…”

“…(Varassin et al, 2001), P. speciosa Gardner (Longo & Fischer, 2006), P. pohlii Mast. (Faria & Stehmann, 2010) and P. actinia Hook (Varassin et al, 2018). Other species, such as Passiflora amethystina J. C. Mikan (Koschnitzke & Sazima, 1997) and P. lutea L. (Holland & Lanza, 2008), show partial genetic self-incompatibility, producing fewer fruits and seeds when self-pollinated.…”

Chemical Composition of the Essential Oils From Leaves and Flowers of Passiflora sexocellata and Passiflora trifasciata

“…Regarding Passiflora family and its nectar production dynamic, high rates of nectar like the storage of starch in P. actinia (subgenus Passiflora) have been shown to be associated with structural characteristics of nectaries and pollinator behavior and breeding strategies. 11 For P. biflora (supersection Decaloba) starch storage was also described by Durkee et al (1981). 12 The high content in total acid and alcohols recorded in P. trifasciata, could be considered as an additive mechanism playing a role in the selective pressures exerted on the pollinator species, towards larger and long-distance flight capable bees.…”