Michigan Trees: A Handbook of the Native and Most Important Introduced Species
cc. Buds red-brown; twigs long-hairy; fruit less than 1 inch
long. _C. microcarpa_, p. 75.
aa. Bark of trunk deeply furrowed or shaggy; husk of fruit more than 1/8 inch thick.
b. Twigs more or less pubescent; buds more or less pubescent.
c. Buds 1/2-3/4 inch long, densely hairy; outer bud-scales deciduous in autumn; twigs brownish; fruit 1-1/2-2 inches long. _C. alba_, p. 73.