Format: ORAL

Peter W. Fritsch1, Andrew A. Crowl2, Bruce A. Sorrie3, and Paul S. Manos4

1 Botanical Research Institute of Texas, Fort Worth Botanic Garden, Fort Worth, Texas, USA 2 Florida Museum of Natural History, University of Florida, Gainesville, Florida, USA 3 Coker Herbarium, North Carolina Botanical Garden, University of North Carolina, Chapel Hill, North Carolina, USA 4 Department of Biology, Duke University, Durham, North Carolina, USA

The true blueberries (Vaccinium sect. Cyanococcus) constitute a clade of about nine to 24 species in temperate North America. This group served as a model system during the Modern Synthesis for examining the origins, prevalence, and diversification of polyploidy in nature, and remains intensively studied because of its economic importance as a food crop. Nonetheless, its taxonomy and evolutionary history is still uncertain, particularly regarding the relative importance of allo- versus autopolyploidy in the evolution of the group, the extent to which levels of ploidy concord with species boundaries, and the utility of the morphological characters traditionally used for delimiting taxa. To address these knowledge gaps, we have collected over 750 silica-gel-dried leaf samples from natural populations with herbarium vouchers and photographs, nearly 500 of which have been analyzed with flow cytometry to estimate ploidy. A robust diploid phylogenetic estimate has been generated for 36 samples of known ploidy with a target-enrichment phylogenomic approach. To this diploid framework we have added polyploids in several ways to test their evolutionary origins. We found a strong correlation of leaf and stem stomata size and density with ploidy across the clade. With the knowledge gained from these studies, we have examined thousands of herbarium specimens from key U.S. herbaria to begin the process of a comprehensive taxonomic revision that will uniquely include expansive species descriptions, specimens cited, and distribution maps. Progress indicates that the revision will vary substantially from prior work, e.g., it includes the taxonomic resolution of two polyploid species to which names have been extensively misapplied, the resurrection of a localized polyploid endemic currently buried in synonymy, and the discovery of two diploids with unique morphology and localized geographic distribution that may represent undescribed species. We also discovered a morphological means to discern rabbit-eye blueberry cultivars that have escaped from cultivation.