Of the 300 oaks known in the world, 55 are native to North America, and most of these are in the eastern United States. The oaks make up the largest group of forest trees native to New York. In all there are 16 species of oaks native to this state. They grow under a wide range of conditions and show wide variations in form and other distinguishing characteristics. The oaks of New York do not thrive in the high forests of the mountains; therefore, representatives of the family found in the Adirondack section are in the sheltered valleys of the foothills. South and westward in the drainages of the Susquehanna, Genesee, and Alleghany Rivers, they become very plentiful in variety and number.

The best way to get acquainted with New York oaks is to divide them into two major groups, the one group to comprise the white oaks and the other the black oaks. It is easy to place the oaks of New York in these two groups by remembering the following characteristics of each:

The white oaks - The leaves of the members of the white-oak group have rounded lobes (not bristle-tipped), and the kernels of the acorns are usually sweet. All the oaks of this group mature their acorns in a single season; for this reason they are sometimes called "annual oaks." The most important members of the group in New York are white oak, swamp white oak, bur oak, post oak, and chestnut oak.

The black oaks - The leaves of the members of the black-oak group have bristle-tipped (not round-lobed) leaves, and the kernels of their acorns are usually bitter. All the oaks of this group require two seasons to mature their acorns; for this reason the representatives of this group are sometimes called "biennial oaks," which means two-year oaks in contrast with the one-year white oaks. The immature acorns are very helpful in recognizing the members of the black-oak group, especially during the winter months when the trees are without leaves. The most important members of this group in New York State are black oak, red oak, scarlet oak, and pin oak.