Oaks are an important source of lumber. Oak wood is heavy, hard, and strong, and it has a beautiful grain. Manufacturers use it for furniture, barrels, and railroad ties. The wood and bark of some oaks contain tannin, a bitter substance used in the preparation of leather. Cork comes from the bark of certain oaks.
Acorns are an important source of food for wildlife.
In the past, many Indians of North America used acorns for food. Today, oaks are grown as ornamental trees worldwide. More than 300 species of oaks are native to North America. Only about 60 of these grow north of Mexico. The trees in these two groups differ chiefly in the shape of their leaves and in how long it takes their acorns to mature.