The largest yellow birch has a radius of 40 inches, the paper birch almost 36 inches, the river birch about 33 inches and the sweet birch 30 inches. The white birch has a radius of up to 12 inches, and the gray birch 6 inches. Of the 12 species of birch in the temperate regions of North America, yellow, sweet and paper birch have the most commercial importance, writes professor Daniel L. Cassens of Purdue University.
About this Author
Rogue Parrish has written two travel books and edited at the "The Baltimore Sun," "The Washington Post" and the Alaska Newspapers company. She began writing professionally in 1975. Parrish holds a summa cum laude Bachelor of Science degree in journalism from the University of Maryland.