Advisors
: Dr. Jennifer Ackerfield, Dr. Gregory Ragland, Dr. Robert Raguso and Dr. Andrew Wilson
Date: July 24, 2026
Time: 9:00am – 10:00am
Location: Denver Botanic Gardens Freyer-Newman Center
Join: https://teams.microsoft.com/meet/276314548960353?p=7nxPQb2OBFA2OAgMSI
Meeting ID: 276 314 548 960 353
Passcode: VT2Hj38H
Genetic and Aromatic Signatures in the Polemonium Viscosum Complex: A Combined Approach to Species Delimitation
The Polemonium viscosum complex, a clade of alpine angiosperms, has a long history of taxonomic confusion, with closely related taxa repeatedly conflated based on overlapping morphology, phenology, ecology, and geography. Two taxa in particular, P. confertum and P. viscosum, are morphologically similar but broadly associated with different floral scent profiles, with P. viscosum described as “skunky” and P. confertum described as “sweet”. By integrating floral scent analysis with high throughput phylogenetics, this study finds that P. confertum is genetically and chemically distinguishable from P. viscosum, supporting its recognition as a separately evolving lineage under the general lineage species concept. Genetic differentiation between P. confertum and P. viscosum exceeded that observed between P. viscosum and P. brandegeei, an unexpected pattern given the latter’s consistent recognition as a separate taxon. Floral scent composition also varied between P. confertum and P. viscosum, but this result should be interpreted cautiously as it is based on a floral scent sample subset with limited P. confertum sampling. A notable exception emerged at Pennsylvania Mountain, where populations morphologically identified as P. confertum resolved genetically as P. viscosum, despite modest but statistically significant scent differences from P. viscosum. Chemical and phylogenetic approaches provide a powerful method for investigating species boundaries in taxonomically challenging plant groups, with implications for how alpine plant diversity is understood and conserved. Although initially designed to resolve species boundaries between P. confertum and P. viscosum, these results raise a further question: whether P. brandegeei is a truly separate lineage from P. viscosum.