Online tools for identifying leaves include tree databases from local nature preserves, government park services and local university extension programs. The Arbor Day Foundation, the Natural History Museum in London and Butler University all offer online tools.
Ideally, an individual should consult tools provided by a local organization that prioritizes leaves likely to be found in the area over specimens from other regions. The Arbor Day Foundation is a U.S. national organization, although it offers regionally specific identification tools. The Natural History Museum in London offers a database geared towards European urban centers. The Butler University tool is best for residents of the Midwest.