Cleared leaves are modern leaves that have been bleached and stained to make their venation patterns more visible. Leaf shape, venation, and features of the margin, base and apex constitute important taxonomic and physiognomic characters. For more information on leaf terminology, download the Manual of Leaf Architecture. For the paleobotanist, cleared leaves aid in identifying fossil leaf compressions. To learn more about the use of fossil leaves in inferring paleoclimate, visit the Climate Leaf Analysis Multivariate Program (CLAMP) website.
UCMP houses the Daniel I. Axelrod and the Berkeley collections, comprising over 2000 slides of modern leaf taxa. Leaves of the Axelrod collection are mounted in plexiglass and are in good archival condition. However, the Berkeley collection is mounted between glass with the mounting medium Permount and is unfortunately deteriorating due to oxidation of this medium. Therefore, putting the cleared leaf images online is in part a conservation measure, with the ultimate goal of having the entire cleared leaf collection available online and CD to serve as teaching and research tools.
Data records for both collections are now available in the online database. JPEG images are being incorporated with the specimen records, beginning with the Axelrod collection. Some images are also available in higher resolution “Zoom and pan” mode (all eventually will be), which gives finer detail of the venation, epidermis and margin areas and in many cases insect and fungal damage, information vital for paleoecological studies.
Locality information: For leaves in the Axelrod collection, the locality data, if any, appear directly on the slide label. The Berkeley collection generally has good locality information, since many of the cleared leaves are from herbarium specimens housed at UC Berkeley’s University and Jepson Herbaria.
Additional information: The Berkeley cleared leaves are linked directly to their UC Berkeley Herbarium online records using the UC Herbarium Accession ID number. Clicking on this number will bring up all information the herbaria have for a particular specimen, but please note that only the herbaria’s California collection is currently web accessible.
In addition, cleared leaf specimen images are linked to the ITIS report, the USDA plants database, CalPhotos database, and Google image search, providing additional images, taxonomic and geographic information for the taxon of interest.