While at the Smithsonian Institution Leo J. Hickey began National Cleared Leaf Collection (referred to as the NCLC-H) in 1969 as part of his research on the systematic distribution of the leaf characters of the flowering plants in relation to the evolution of a group. The NCLC-H consists of over 7,000 cleared, stained and mounted extant leaves. It stands as the major community resource in the area of foliar morphology for plant systematists and paleobotanists around the world. The NCLC-H was moved to Yale Peabody Museum on a long-term loan agreement when Leo Hickey came to the Peabody Museum of Natural History as Director in 1982. Sadly, Dr. Leo Hickey passed away in February 2013. The NCLC-H was returned to Smithsonian National Museum of Natural History in May, 2014.