Research in the Sessa lab focuses broadly on plant systematics and understanding the evolutionary and ecological processes that shape plant diversity. Lab members work on a number of projects around this central theme, with phylogenetics as the unifying conceptual framework. Phylogenies inform our research in a number of related areas, including understanding basic relationships among taxa, patterns of reticulate evolution, diversification rates and biogeographic history of organisms, community phylogenetics, and trait evolution using comparative methods. Organismally, we have a strong focus on the seed-free vascular plants: ferns and lycophytes (traditionally collectively called pteridophytes). Our work, whether on ferns, lycophytes, or other systems, uses data collected in field and experimental studies and generated via Sanger and next-generation sequencing. We integrate techniques from several disciplines, including computational and evolutionary genomics, phylogenetic systematics, physiological ecology, and traditional specimen-based botany. There are many ongoing projects in the lab, including those listed below.