At this festive time of year, when many people are bringing trees into their homes to decorate for the holidays, we are going back to our story of a pioneering scientist who made it her mission to ensure that plants traveling across borders did not carry any diseases. It was in 1909, that the Mayor of Tokyo sent a gift of 2,000 prized cherry trees to Washington, D.C. But the iconic blossoms enjoyed each spring along the Tidal Basin are not from those trees. That’s because Flora Patterson, who was the Mycologist in Charge at the USDA, recognized the original saplings were infected, and the shipment was burned on the National Mall. In this episode, we explore  Patterson’s lasting impact on the field of mycology, starting with a blight that killed off the American chestnut trees, and how she helped make the USDA’s National Fungus Collection the largest in the world.