36 HOUGH'S AMERICAN WOODS. 



PHYSICAL PROPERTIES. Wood heavy, hard and strong, of a pinkish- 

 brown color with rather scant, whitish sap-wood. Specific Gravity, 

 0.7405; Percentage of Ash, 0.19; Relative Approximate Fuel Value, 

 0.7391; Coefficient of Elasticity, 108507; Modulus of Rupture, 1054; 

 Resistance lo Longitudinal Pressure, 504; Resistance to Indentation, 

 202; Weight of a Cubic Fool in Pounds, 46.15. 



USES. This is not a particularly valuable timber and is not distin- 

 guished in usage from the Eed Oak and other allied species. It is used 

 in cooperage, for chairs, etc., and to some extent in interior finishing. 

 As a fuel it is of rather inferior grade. The bark is sometimes used for 

 tanning purposes. 



.MEDICINAL PROPERTIES. None are known of this species. 



ORDER BETULACEJfE: BIRCH FAMILY. 



Leaves simple, alternate, straight-veined and furnished with stipules which fall 

 away early. Flowers mostly naked, monoecious, both kinds in catkins, 2 or 3 together 

 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, albumeuless, 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, TOURN. 



Leaves ovate, serrate, these, with the twigs, especially the latter, 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 summer 

 and remaining dormant during the following winter to open and perform their func- 

 tion 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 bractlets 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 brauchlets dotted, inner bark more or less aromatic and of pleas- 

 ant flavor. 



70. BETULA POPULIFOLIA, MARSHALL. 

 WHITE BIRCH, POPLAR-LEAVED BIRCH, OLD-FIELD BIRCH. 



Ger., Pappelbldttrige Birke; Fr., Douleau blanc; Sp., Abedul bianco. 



SPECIFIC CHARACTERS: Leaves deltoid with long tapering point, more or less trun- 

 cate at base, unequally serrate or obscurely lobed, smooth and shining both sides, 

 resinous dotted when young, of firm texture and with long, slender and smooth 

 petioles. Fruit in cylindrical, pendulous catkins, an inch or more in length, with 

 long slender peduncles; scales glabrous, with short, roundish, diverging lobes, and 

 falling away freely when mature; wing of nutlet much broader than its body. 



(Popnlifolia is from Lat. popnhis, pnplar, and folium, leaf, alluding to the resem- 

 blance of the leaves to those of the poplar.) 



