Floral biology, pollinators and breeding system of Passiflora chrysophylla (Passifloraceae), a South American passion vine

Context Knowledge of the reproductive biology of plants is fundamental for conservation, especially of the ones with a limited distribution. Aims The sexual reproduction of the small-ranged Passiflora chrysophylla Chod. was studied. Methods Controlled pollinations were performed to assess the breeding system, whereas floral traits and visitors (identity, frequency, activity on the flowers, dimensions and pollen load) were analysed to assess the pollination mechanism. Key results Self-compatibility was partial. Anthesis was matinal. The odour emitted by the corona was sweet, whereas the odour emitted by the persistent sepals and bracts was similar to that of the leaves. Contrasting concentric circular reward guides were present in the visible and UV spectra. Nectar concentration was high, the volume increased throughout anthesis and, if removed, nectar was replenished only once during the flower lifespan. Style movements towards the anthers determined male and hermaphroditic phases in most of the flowers; in a few flowers (smaller, scented and nectarless), styles remained apart from the anthers, thus constituting a functionally andromonecious and deceptive automimicry system. The bees Ptiloglossa sp., Thygater analis and Xylocopa augusti acted as pollinators, whereas ants, butterflies and beetles were nectar or pollen thieves and florivores. Conclusions P. chrysophylla is melittophilous and pollinators increase reproductive success. Implications Pollination biology of P. chrysophylla, reported for the first time, would contribute to conservation management of this species with restricted distribution.