118 



BLACK BIRCH. 

 Betula lenta, Linnaeus. 



FORM This tree usually attains a height of 50-60 ft. with a diameter of 1-3 ft., but 

 may reach a height of 80 ft. with a diametel of 5 feet. Trunk rather continuous, sometimes 

 subdivided, bearing long, slender, lateral branches which are ascending on young trees forming 

 a narrow conical crown, or often pendulous on old specimens forming a wide spreading crown. 



BARK On old trunks (Fig. 71) distinctly black, broken into large, thick, irregular plates 

 which are smooth on the surface; on younger parts of the trees (Fig. 70) smooth, shining, 

 very close fitting, reddish-brown, with sweet wintergreen taste and covered with horizontally- 

 elongated lenticels. 



TWIGS During the first summer light green and hairy, later becoming reddish-brown, 

 smooth, shining, with pronounced wintergreen-like flavor. Terminal twigs slender and elongated, 

 while lateral spurs are numerous, stout, and short. 



BUDS Alternate, about J of an inch long, conical, sharp-pointed, shining, covered with 

 reddish-brown overlapping scales with downy margins. Three bud-scales usually visible on buds 

 of terminal shoot and fiom 5-8 on lateral spur shoots. 



LEAVES Alternate, simple, ovate, usually heart-shaped at base, serrate on magrin, long- 

 pointed at apex, dark green above, pale green below, 2i-5 inches long, li-3 inches wide. 



LEAF-SCABS Alternate, small, semi-oval in outline, containing 3 rather small, equidistant 

 bundle-scars. 



FLOWERS Appear about April before the leaves. Staminate formed in fall, remaining over 

 winter as aments about I of an inch long, in clusters of usually three, which .elongate to 

 about 3 or 4 inches the following spring. Pistillate about i-f of an inch longi slender, and 

 pale green. 



FRUIT A strobile about li-2 inches long, sessile, smooth, erect, with smooth 3-lobed 

 scales and small winged nutlets. Lobes of the scales are about equal in length but the 

 terminal is narrower and sharper-pointed. 



WOOD Diffuse-porous; rays indistinct; heavy, strong, hard, dark brown, with thin yellowish 

 sapwood. Weighs 47.47 Ibs. per cubic foot. Used for furniture, often in imitation of 

 Mahogany, and for interior finish; also substituted for Cherry and occasionally for Hickory. 

 Tree* cut in spring at about the time the buds open, bleed more than any other species, 

 but the sap contains less saccharine material than that of the Maples. 



DISTINGUISHING CHARACTERISTICS The Black Birch, also known as Sweet Birch, and 

 Cherry Birch, can be distinguished from all the other species of Birch in 'Pennsylvania by 

 its close, blackish, cherry-like bark which does not peel off into film-like layers. It closely 

 resembles the Yellow Birch but the latter has yellow bark which peels off into thin film- 

 like layers. The twigs have a distinctly wintergreen-like flavor which is absent in the other 

 species. The scales of the fruit of the Black Birch are smooth about equally lobed while 

 those of the Yellow Birch are hairy and irregularly lobed. 



RANGE Newfoundland to Florida, west to Ontario, Illinois and Tennessee. 

 DISTRIBUTION IN PENNSYLVANIA Common throughout the State, and locally frequent. 



HABITAT Usually found in rich soil and on dry slopes but also common on rocky mountain 

 slopes and tops. Commo?i on the rocky ridges ol the South Mountains in Pennsylvania. 



IMPORTANCE OF THE SPECIES The Birches, next to the Hickories, furnish the best fuel 

 wood of all the native species of Pennsylvania. The wood of Black Birch ranks . high as a 

 fuel wood and is becoming more important in the manufacture of furniture, especially as a 

 substitute for Mahogany and Cherry. This tree also yields an oil sold as a substitute for 

 wintergreen. While this species has many good qualities still it is a slow grower and when 

 quite young is subject to the attack of fungi, which materially decrease the technical value 

 of the wood. It is not of sufficient importance to be regenerated artificially but should be 

 developed where it appears naturally. This species occurs naturally upon extremely rocky 

 ridges and may be a very desirable gpecies in establishing protection forests upon steep 

 mountain slopes and rocky mountain tops.' 



