Researchers have succeeded in constructing, from scattered data, a world map of the diversity of tree species. Climate plays a central role for its global distribution; however, the number of species ...

Steve Nix is a member of the Society of American Foresters and a former forest resources analyst for the state of Alabama. Leaf shapes play an important role in tree identification, providing key ...

Chicago's eastern boundary is formed by Lake Michigan, and the city is divided by the Chicago River into three geographic sections: the North Side, the South Side and the West Side. These sections ...

Since Philadelphia is arranged on a grid system, the mostly one-way roads are easy to navigate. Helpful maps are posted along street corners across the city – watch for the "Walk! Philadelphia" signs ...