Almost all of the maple used in building work comes from the hard sugar maple, which is most abundant in the region of the Great Lakes, but which is also found from Maine to Minnesota and southward to Florida. The trees are of medium to large size and form quite considerable forests. They are so abundant in Canada that the maple is the national tree, and the national emblem is a maple leaf. The wood when finished presents a very pleasing appearance, and ranks as one of the best of the hard woods in this respect. It is heavy and strong, of fine texture, and often has a fine wavy grain which gives the effect known as "curly." Other defects which add to the beauty of the grain occur in what is called "blister" and "bird's-eye" maple. These defects are the result of twisting of the fibers which make up the woody structure of the tree, and the maples seem to show them more frequently than any of the other trees, though they sometimes are to be found in birch and various other woods. The color of the sapwood is a creamy white while the heartwood is tinged with brown. The lumber shrinks moderately, stands well, is easy to work, and is tough, but not very durable when subjected to exposure. The finished wood takes an excellent polish. It is most commonly employed for floors, and in other positions where a good wearing surface is required, as well as for ceiling and paneling, and other interior finish.