70. BETULA POPULIFOLIA WHITE BIRCH. 37 



A small and graceful tree attaining the height of 30 ft. (9 m.), or 

 rarely more, with a trunk not often 15 in. (0.45 m.) in diameter, clothed 

 with a smooth, chalky-white bark, which separates with some difficulty 

 into thin sheets and peels off around the tree. Its branches are numer- 

 ous, slender and upright at first, but with drooping sprays of a purplish- 

 brown color. The foliage is rather thin and always agitated by the 

 slightest wind like that of the poplar, owing to the length of its slender 

 petioles. 



HABITAT. New Brunswick, the valley of the St. Lawrence and south- 

 ward to Delaware, thriving in dry and very poor, sandy soil. 



PHYSICAL PROPERTIES. Wood light, soft, not strong, fine-grained 

 and taking a fine satiny polish. It is of a light-brown color with brown- 

 ish-white sap-wood. Specific Gravity, 0.5760; Percentage of Ash, 0.29; 

 Relative Approximate Fuel Value, 0.5743; Coefficient of Elasticity, 

 7x5970; Modulus of Rupture, 778; Resistance to Longitudinal Pressure, 

 348; Resistance to Indentation, 129; Weight of a Cubic Foot in Pounds, 

 35.90. 



USES. Valuable in the manufacture of small wooden-ware, as clothes- 

 pins, spools, shoe pegs, tooth-picks, etc.. and is used to some extent for 

 paper-pulp and fuel. 



MEDICINAL PROPERTIES are not officinally recognized of this species. 



ORDER SALIC ACE.K : WILLOW FAMILY. 



Leaves alternate, simple, undivided and furnished with stipules, which are either 

 scale-like and deciduous, or leaf-like and persistent. Flowers dioacious, both kinds 

 in catkins, one under each bract or scale of the catkin, and destitute of both calyx 

 and corolla, or the former represented by a gland-like cup; ovary 1 to 2-celled; styles 

 wanting, or 2 and short; stigmas often 2-lobed. Fruit a 1 or 2-celled, 2-valved pod, 

 with numerous seeds springing from 2 parietal or basal placentae and furnished with 

 long, silky down; seeds ascending, anatropous, without albumen; cotyledons flat. 



Trees or shrubs of rapid growth, light wood and bitter bark. 



GENUS SALIX, TOURN. 



Leaves generally narrow, long and pointed and usually with conspicuous stipules; 

 bud scales single. Flowers appearing before or with the leaves in terminal and lateral 

 cylindrical, imbricated catkins, the scales or bracts of which are entire and each sub- 

 tending a flower, which is without calyx, and bears at its base 1 or 2 small nectiferous 

 glands. Sterile flowers with 2 (but sometimes more) distinct or united stamens. Fer- 

 tile flowers : ovary ovoid lanceolate, taper-pointed ; style short; stigmas 2. short and 

 mostly bifid. Fruit a 1 -celled pod, dehiscent at maturity by two valves which roll 

 back at the summit to liberate the numerous minute comose seeds. 



Trees and shrubs with lithe round branches and growing mostly along streams and 

 in moist localities. (Snlix is from the Celtic sal, near and Us, water, alluding to the 

 favorite locality of the willows.) 



