3100 



Chapter 25 



Figure 25-10. — Scanning electron micrograph of a paper sheet formed from hardwood 

 cells; wide, short vessel elements are evident among the long narrow fibers. (Photo 

 from Cdte 1980.) 



to 1.85 in black tupelo. Length-to-thickness ratio varied from 207 in American 

 beech to 403 in paper birch, and fibril angle from 6.3° in sugar maple to 19.4° in 

 shagbark hickory. In addition to the five hardwoods commonly found in the 

 South (American elm, sweetgum, black tupelo, shagbark hickory, and white 

 oak), the study included paper birch {Betula papyrifera Marsh.), sugar maple 

 {Acer saccharum Marsh.), quaking aspen {Poplus tremuloides Michx.), Ameri- 

 can beech {Fagus grandifolia Ehrh.), and red alder {Alnus rubra Bong.). 



