Seed Production and Pollinator Dependence in Native Wildflowers: Guiding Species Selection for Conservation Plantings

The diversity of plants and their animal pollinators is in decline due to anthropogenic pressures such as habitat loss, pesticide use, and agricultural intensification. Approximately 78% of angiosperms rely on animal-mediated pollination, yet data on the pollination biology of many native wildflower species is lacking. We investigated the pollination biology of eight wildflower species native to the southeastern United States, including Bidens laevis, Desmanthus illinoensis, Echinacea purpurea, Eryngium yuccifolium, Gaillardia pulchella, Monarda punctata, Verbesina alternifolia, and Verbesina virginica, which are either recommended by the USDA-Natural Resource Conservation Service or the Xerces Society to enhance native pollinator habitat. We evaluated each species' dependence on insect pollinators through an insect exclusion experiment and documented insect floral visitors via sweep netting surveys followed by a plant-pollinator network analysis. For most species, open-pollinated inflorescences produced significantly more and/or heavier seeds per inflorescence compared to those excluded from insect visitors, indicating a high degree of pollinator influence. In comparison, several species exhibited potential for self-pollination. A total of 1417 insects, representing 73 genera/species from 21 families and 4 orders, were observed visiting the wildflower species. These findings indicate the importance of insect pollinators for maximizing seed production and quality in these native wildflower species and underscore the importance of considering the pollination requirements when selecting species for conservation plantings. Our results highlight that some native wildflower species reproduce and set seed in the absence of pollinators, making them valuable for providing floral resources in degraded habitats, while strongly pollinator-dependent species may be better suited for conservation plantings in areas with robust or recovering pollinator communities.