800 million year old fossils of cyanobacteria, Spitsbergen (each cell about 4 microns in diameter)Plant fossils provide us with key insights into evolutionary milestones and past environments spanning tens of millions of years. The Harvard University Herbaria has a rich collection of macro and microfossils from across green plants, especially from the United States and Europe.

Plant Evolution
Research in the Knoll lab focuses on inferring large scale evolutionary patterns in plants using data from fossils and extant species. Recent projects have sought to characterize the evolution and development of leaves in vascular plants.