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

Abstract

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-rangedPassiflora chrysophylla Chod. was studied. Methods. Controlled pollinations were performedto assess the breeding system, whereas floral traits and visitors (identity, frequency, activity onthe 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 coronawas sweet, whereas the odour emitted by the persistent sepals and bracts was similar to that of theleaves. 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, nectarwas replenished only once during the flower lifespan. Style movements towards the anthersdetermined 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 functionallyandromonecious and deceptive automimicry system. The bees Ptiloglossa sp., Thygater analisand Xylocopa augusti acted as pollinators, whereas ants, butterflies and beetles were nectar orpollen thieves and florivores. Conclusions. P. chrysophylla is melittophilous and pollinators increasereproductive success. Implications. Pollination biology of P. chrysophylla, reported for the firsttime, would contribute to conservation management of this species with restricted distribution