Flower Visitation, Floral Traits, and Reproduction of Nicotiana glauca (Solanaceae) in an Urban Landscape

ABSTRACT

Urban environments can generate substantial spatial and temporal variation in pollinator assemblages, floral traits, and resource availability, yet how plant reproduction is maintained under such heterogeneous conditions remains poorly understood, particularly in tropical cities. In Nicotiana glauca (Solanaceae), floral traits and pollinator assemblages vary among natural populations, but information from urban environments is lacking. We investigated pollination dynamics and reproductive success of N. glauca across a heterogeneous urban landscape in the high tropical Andes by integrating flower visitation, floral trait variation, functional morphology, and reproductive output. Flower visitation varied strongly among visitor groups, times of day, and urban regions. Hummingbirds were the only legitimate pollinators, whereas bees acted exclusively as nectar robbers. We report Colibri coruscans and Elliotomyia chionogaster as pollinators of N. glauca for the first time. Despite pronounced spatial and temporal variation in floral traits and visitor assemblages, including complete spatial turnover between hummingbird species, fruit set remained consistently high (> 90%) across all urban regions. No fruits were produced in pollinator‐excluded flowers, suggesting dependence on animal‐mediated pollination. Although flower tube length generally exceeded hummingbird bill length, both species appeared functionally compatible with the flowers and carried pollen on their beaks during visitation. Our results show that N. glauca maintains high reproductive success across heterogeneous urban environments, through hummingbird‐mediated pollination, highlighting the resilience of some plant–pollinator interactions in rapidly urbanizing tropical landscapes.