About.com: Top 100 Trees
Find information on more than 100 trees in North America
Ariadne's Trees and Forests
Glossary of tree-related terms; articles on California trees, hiking, and meditation.
British Trees
Guide to the native trees of Britain, plus links to other web resources on forestry and conservation of British Native trees, including forest conservation organizations.
Catalog of the Woody Plants of Oklahoma
Descriptions, images, and range maps.
Common Trees of Pennsylvania
Guide to common trees with laymans descriptions of each tree, and a simple key to start with. Line drawings of leaves and fruit.
Conifers in the Pacific Northwest
A site that covers common conifers only. Uses an interactive web based dichotomous key.
Forest Trees of Florida
Descriptions and images of over 70 species.
Goo's Tree Encyclopedia
Names and illustrations of Japanese trees.
Identification of Common Trees of Iowa
An interactive guide to trees, using a simple visual dichotomous key.
Identifying Trees of Michigan
A page on the common trees of Michigan with a key.
The Tree Register of the British Isles
Historical, ancient, and biggest trees of Great Britain and Ireland.
Top Trees UK
Searchable database of notable UK trees. Tree quotes, news, photo galleries, and forums.
Tree Atlas of the Panama Canal Watershed
Species accounts with images and maps, arranged by scientific name, tanomomy, and common name. In English and Spanish.
Trees and Shrubs of Ontario
Designed to assist those interested in learning some of the common trees and shrubs found in the province.
Trees of Alabama and the Southeast
Brief text and numerous photos of both native and planted trees. Includes section illustrating terminology with photographs.
Trees of Eastern North American Forests
Descriptions and images of various trees native to the eastern forests of North America.
Trees of Ilalo
Photographic guide to the trees of Ilalo, a mountain in the inter-Andean Valley near Quito, Ecuador.
Trees of Ottawa
A photographic index of tree species that grow in Ottawa, Ontario, Canada.
Trees, Shrubs, and Woody Vines of Central North Ca
Photographs and information on over 160 species, identification key, and full species lists for two counties.