14 BULLETIN" 1050, U. S. DEPARTMENT OF AGRICULTURE. 
BIRCH. 
Sweet birch (Betula lenta Linn.) ; yellow birch (Betula lutea Michx. f.). 
Birch Family (Betulace^e). 
other names. 
Sweet birch is also known as cherry birch, black birch, and ma- -~ 
hogany birch. f 
Yellow birch is also known as gray birch, silver birch, and swamp 
birch. 
The heartwood of both species is usually sold as " red birch " and 
the sapwood as " yellow birch." 
Other species of birch are rarely cut into lumber. 
WHERE GROWN. 
Sweet birch grows within an area that extends from Newfoundland 
to eastern Iowa, and south to northern Florida. It is of commer- g 
cial importance, principally in the East, from New York State south ^ 
along the Appalachian Mountains, although it is cut as far west as 
Wisconsin. 
Yellow birch occurs from Newfoundland to northern Minnesota, 
and through the northern States to eastern Tennessee, North Caro- 
lina, and Delaware. It is most abundant and reaches its largest size 
in northern New England and New York and in northern Michigan 
and Wisconsin. 
PHYSICAL PROPERTIES. 
Although sweet birch averages slightly heavier and harder than 
yellow birch, the difference is so little that usually no distinction is 
made between the two species when used in the form of lumber. 
Both species are hard, heavy, and strong in bending. f 
Birch has somewhat of a tendency to warp, but not so much as 
red gum and other species with decidedly interlocked grain. 
The heartwood is reddish brown; the sapwood, which is often 
wide, is practically white. Much sapwood is used in the manufac- 
ture of furniture with a mahogany finish. It is difficult to hide its 
identity since any wear or fracture is likely to disclose the white 
wood underneath the finish. 
STRUCTURE. 
The pores in birch are of such size that they can barely be seen 
in good light without a lens on the smoothly cut end surface. On 1 
the longitudinal dressed surface they appear as very fine grooves. 
They are almost uniform in size throughout each annual ring, 
although occasionally they are noticeably smaller toward the end of 
each year's growth. (See fig. 9.) The annual rings are defined by 
fine lines. 
