Betula leopoldae is an extinct species of birch in the family Betulaceae. The species is known from fossil leaves, catkins, and inflorescences found in the early Eocene deposits of northern Washington state, United States, and similar aged formations in British Columbia, Canada. The species is placed as basal in Betula, either as a stem group species, or an early divergent species. History Betula leopoldae fossils have been identified from a number of locations in Western North America, the 49 million year old Klondike Mountain Formation near Republic, Washington along with the Allenby Formation near Princeton, the Falkland fossil site near Falkland, and McAbee Fossil Beds both of the Kamloops Groups Tranquille Formation, and the Quilchena fossil site near Quilchena, British Columbia. In general, the geologic ages for the Okanagan Highland locations are of Early Eocene, with the sites that have current uranium-lead or argon–argon radiometric dates indicating Ypresian ages, while the undated sites or those given older dates being possibly slightly younger and Lutetian in age. Betula leopoldae was described from a series of type specimens collected in the Republic, Washington area during the early 1980s. The paratype leaf, UW 31256 plus the holotype leaf UW 39722, are in the paleobotanical collections of Burke Museum, while the counterpart for the holotype, UCMP 9286 is in the University of California Museum of Paleontology in California. Working from these two specimens, the species was studied by Jack A. Wolfe of the University of California and Wesley C. Wehr of the Burke Museum. They published their 1987 type description in a United States Geological Survey monograph on the North Eastern Washington dicot fossils. The specific epithet leopoldae is a matronym recognizing paleobotanist and conservationist Estella Leopold, though this was not noted in the type description. In a paper which appeared that same year, Peter Crane and Ruth Stockey described a series of B. leopoldae leaves along with catkins, flowering bodies, and pollen from the Allenby Formation. Crane and Stockey noted B. leopoldae to be the oldest reproductive plus vegetative record for a Betula species at that time. A B. leopoldae leaf from the Klondike mountain formation was figured by Conrad Labandeira in 2002 which displayed distinct interior foliage feeding damage from insect feeding, in which a series of four leaf blade sections had been removed between successive secondary veins. Classification While Wolfe and Wehr did not detail any subgenus placement in the original