Are Native Palms Pollinator Hogs? A Field Experiment in Pine Rocklands of Southern Florida

Plants blooming simultaneously may interfere with each other's pollination (competition for pollinators) or enhance each other's pollination (pollinator sharing). In this study we asked the question: What is the effect of native palm flowering on the pollination of a native wildflower species? Using potted plants of pineland golden trumpet Angadenia berteroi (Apocynaceae), we placed plants with flowers about to open in the field in two positions: within 5 m of flowering palms (Sabal palmetto and Serenoa repens, Arecaceac), and within 5 m of palms that were not flowering. We observed visitors to the flowers of A. berteroi on plants in both situations. We collected the corollas of the one-day flowers to look for pollen deposition on the receptive stigmatic surface. The same flowers were monitored to see if they set fruit. Flowers on plants in both situations were visited, but the ones near flowering palms less frequently. More of the flowers from plants near non-flowering palms had pollen deposited on the stigma, but fruit from flowers presented did not differ between treatments. This experiment demonstrates that flowering palms, with their large floral displays full of pollen and nectar, diminished pollinator visits to one of the most beautiful of the pine rockland wildflowers, resulting in less pollination in A. berteroi. As fire suppression can lead to an understory with overrepresentation of understory palms in pine rocklands, practitioners should manage natural areas to prevent these super-attractive species from hogging floral visitors to the detriment of less numerous native wildflowers.