Leafsnap consists of images of leaves taken from two different sources, as well as their automatically-generated segmentations:
23147 Lab images, consisting of high-quality images taken of pressed leaves, from the Smithsonian collection. These images appear in controlled backlit and front-lit versions, with several samples per species.
7719 Field images, consisting of "typical" images taken by mobile devices (iPhones mostly) in outdoor environments. These images contain varying amounts of blur, noise, illumination patterns, shadows, etc.
The dataset currently covers all 185 tree species from the Northeastern United States.
Cleared Leaf Image Database is an online collection of cleared leaf images from different investigators and labs around the world gathered together in a single place.