BETULACEAE 

 Water Birch. Red Birch 



Betula occidentalis Hook. {Betula fontinalis Sarg.) 



HABIT. A shrub or small tree 20-25 feet high and 12-14 

 inches in diameter; broad, open crown with ascending branch- 

 es; frequently in crowded, dense thickets. 



LEAVES. Ovate; 1-2 inches long and %-l inch wide; acute 

 or acuminate; sharply and often doubly serrate; sometimes 

 slightly lobed; thin and firm; glabrous; dark dull green above, 

 pale yellow-green and minutely glandular below; turning dull 

 yellow in autumn; petioles stout, Yi-Vz inch long, light yellow, 

 glandular-dotted; stipules bright green, slightly ciliate. 



FRUIT. Strobiles cylindrical, pendant (rarely erect) long- 

 stalked, 1-114 inches long; scales ciliate; nutlet slightly nar- 

 rower than wing, 



TWIGS. At first light green and glandular, becoming dark 

 red-brown; marked by horizontal lenticels. Winter buds: V4 

 inch long, ovoid, acute, very resinous, chestnut-brown. 



BARK. Thin (!4 inch); smooth; lustrous dark bronze; marked 

 by pale horizontal lenticels, becoming on old trunks 6-8 inches 

 long and K inch wide. 



WOOD. Rather light and soft; strong; heartwood light 

 brown; sapwood thick, light-colored; not important; used 

 locally for fencing and fuel. 



SILVICAL CHARACTERS. Upper Sonoran and Transition 

 zones; intolerant; shallow root system; reproduction abun- 

 dant in moist, mineral soil; generally along borders of streams 

 in moist mountain valleys and canons. 



Yukon birch, Betula X eastwoodiae Sarg., a hybrid of B. gland- 

 ulosa and B. papyrifera is a small tree or shrub found in swampy 

 sites in northern Alberta and the Yukon. It is characterized by 

 broadly ovate to elliptic leaves \-\V2 inches long; pendulous, 

 cylindric strobiles % inch long, with glabrous scales longer than 

 broad; and close, chestnut-brown bark not readily separating 

 into papery scales. The bog or resin birch, Betula glandulosa 

 Michx., is a shrubby circumpolar form of cold sites. 



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