38 HOUGH'S AMERICAN WOODS. 



gether under a 3-lobed bract or scale. Sterile flowers with distinct stamens and 

 2-celled anthers. Fertile flowers with two thread-like stigmas, and a 2-celled ovary, 

 each cell containing 2 pendulous ovules, becoming by abortion in Fruit, a small, 

 1-celled, 1-seeded nutlet, often with membranous wings; seed anatropous, albumen- 

 less, with flattish, oblong cotyledons which become foliaceous in germination. 

 Trees or shrubs, with bark which separates more or less easily into thin layers. 



GENUS BETULA, TOURNEFORT. 



Leaves ovate, serrate ; these, with the twigs, especially the latter, often spicy aromatic. 

 Flowers appearing in early spring with or before the leaves. Sterile flowers in long, 

 drooping, cylindrical, both terminal and lateral, yellow catkins, appearing in sum- 

 mer and remaining dormant during the following winter to open and perform their 

 function early the next season; bracts 3-lobed, shield-shaped, and beneath each are 

 2 bractlets and 3 flowers with calyx represented by a mere scale, which bears the 4 

 short stamens, each with a single-celled anther. Fertile flowers in cylindrical or ob- 

 long catkins with 3-lobed scales, and beneath each scale are 2-3 naked pistils with- 

 out braclets or calyx. Fruit a small, broadly- winged, scale-like nutlet or samara. 



Trees and shrubs with outer bark horizontally fibrous and usually separable in 

 sheets, that of the branchlets dotted, inner bark more or less aromatic and of pleas- 

 ant flavor. (The ancient Latin name, from Celtic Betu, birch.) 



95. BETULA NIGRA, L. 



EIVER BIRCH, EED BIRCH. 



G-er., ScMuarz-BirJce; Fr., Boulmu noire; Sp., Abcdul neyro. 



SPECIFIC CHARACTERS: Leaves rhombic-ovate, more or less acute at both ends, 

 irregularly doubly serrate, sometimes obscurely 9-13-lobed, 3 in. or less in length, 

 dark green above and until old whitish and downy beneath; petioles about 1-2 in. or 

 less in length, pubescent. Flowers appear with the leaves as described for the 

 genus. Fruit aments erect with soft downy peduncle, ovoid, scales tornentose and 

 with oblong-linear nearly equal lobes; nutlet broadly winged. 



A medium-size tree occasionally attaining the height of 80 ft. (24m.) 

 and 30 in. (0.75m.) in diameter of trunk, with alder-like leaves, reddish 

 twigs, and bark of trunk of a grayish brown color, exfoliating in thin 

 scales and papery patch-like layers with which the trunks of a certain 

 age are literally padded. 



HABITAT. From Massachusetts southward to Florida and westward 

 to Iowa, Kansas and Texas, growing along the banks of streams, ponds 

 and in swampy places. Rare and local in the north, abundant in 

 southward. 



PHYSIC A.L PROPERTIES. Wood i-atlu-r hard, strong, close-grained, 

 compact and with numerous fine medullary rays yielding a smooth 

 finish; with light brown heart-wood and abundant yellowish-white sap- 

 wood, often streaked with brown parenchymatons tissue. Specific Grav- 

 ity, 0.5762; Percentage of Ash, 0.35; Relative Approximate Fuel Value, 

 0.5742; Coefficient of Elasticity, 111322; Modulus of Rupture, 927; Re- 

 sist'ince to Longitudinal Pressure, 438; Resistance to Indentation, 132; 

 \V''i(jht of a Cubic Foot in Pounds, 35.91. 



