The Smith Falls Hybrid Aspen (Populus x Smithii) is a tree species that is a hybrid between the Bigtooth Aspen (Populus grandidentata) and Quaking Aspen (Populus tremuloides). A relict of the Ice Age, these trees are now critically endangered.
The few that remain are located in the Niobrara River valley of the Sandhills of north central Nebraska. They grow in a pocket of spring-branch canyons in an area known as the “biological crossroads of the world” where six ecosystems converge.