Smithsonian Yale Peabody Museum of Natural History

The National Cleared Leaf Collection-Hickey

Leo J. Hickey1, 2 and Shusheng Hu1

1Division of Paleobotany, Peabody Museum, Yale University, P. O. Box 208118, New Haven, CT 06520

2Department of Geology and Geophysics, Yale University, P. O. Box 208109, New Haven, CT 06520



The National Cleared Leaf Collection-Hickey (NCLC-H) consists of more than 7,000 glass slides of cleared and stained extant leaves mounted between sheets of optical quality, distortion-free glass.
The NCLC-H is currently arranged alphabetically by family, then by genus and species. There are approximately 321 families and 1,300 genera, including herbaceous, parasitic, Arctic, alpine and derived groups such as the Asteridae, in an effort to elucidate the full range of dicotyledonous leaf morphological patterns. Also, there are a significant number of extinct and endangered species, such as Canacomyrica monticola from New Caledonia. The collection presently covers floras from South America, North Central America, Oceania and Asia. Most of the leaves have been taken from herbarium collections, with some prepared using fresh or fluid-preserved specimens. Each specimen is vouchered to an authoritatively identified herbarium sheet. Once collected, the leaves are cleared in bleaching solutions, stained and then mounted in resin between sheets of optical glass. Over the years various mounting mediums have been used, including Coverbond, Histoclad, Cytoseal and Canada balsam. The majority of leaves are mounted on four different sizes of glass: 2"x 3", 4"x 3-1/4", 4"x 5" and 5'x 4-1/2". Labels are also placed between the glasses as the leaves are mounted. The size, scope, documentation, and the quality of the mounts make the NCLC-H the most important database of leaf architecture in the world. At the present time, the NCLC-H provides the main source of documentation for the systematic description of leaf architectural variation among the dicotyledons and has been the basis for the current system of leaf architectural classification, fossil and modern plant identifications, ecological and paleoecological studies, as well as ongoing studies into the ontogeny of leaf venation.



Leo J. Hickey began the NCLC-H at the Smithsonian Institution 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 the group. When Hickey came to Yale University in 1982, the NCLC-H was loaned to the Yale Peabody Museum of Natural History for Hickey's ongoing research. The NCLC-H was returned to Smithsonian National Museum of Natural History in May, 2014.


Scope of Coverage

Geographic and Taxonomic Distributions of National Cleared Leaf Collection-Hickey



Geographic Distribution

South America


North America


Central America






Other (Australia, Africa, Europe, Middle East and Caribbean)





Taxonomic Distribution









Dicotyledons 97%
Monocotyledons 1%



Terms of Use

The copyright of all NCLC-H images belongs to Yale Peabody Museum of Natural History. The Museum grants permission for personal or scholarly use of images, text and data for reproduction for personal, educational or academic purposes without personal or corporate gain (e.g., for study, teaching, theses, and published research). Commercial use of these images is prohibited without written permission from Peabody's Division of Paleobotany.



We would like to thank the following volunteers for their efforts in photographing the collection and providing curatorial support.


Whitney Barlow
Donna Beeson
Serra Vidinli Dedeoglu
Michelle Garcia
Gabriela Gonzalez
William Guth
Zoe Kitchel
Philip Kuchuk
Steven Mordarski
John Petrucelli
Ornella Rossi
Carl Russell
Jared Shayne
Robert Swerling
Cecilia Tenorio


We would like to thank the following Yale students:


Alyssa Cheung
Joanna Liu
Ivette Lopez
Paul Pena


Thanks also go to:


Linda Klise, former Senior Collections Manager, Division of Paleobotany, Yale Peabody Museum
Larry Gall, head of the Computer System Office, Yale Peabody Museum
Sally Palatto, Graphic Designer, Yale Peabody Museum
Harry Shyket, Digital Media Specialist, Yale Peabody Museum
Tim White, Director of Collections & Operations, Yale Peabody Museum