The Trees of Wyoming. 97 



Birch Family. 



(Betulacece) 



This family is represented by three Birches and one 

 Alder. One of the Birches (Betula glandulosa Michx.) is 

 only a small shrub occurring in swales in the mountains, 

 so need not be mentioned further in this bulletin. None 

 of the members of this family become very large in Wyo- 

 ming, but they are to be recognized as true trees. No 

 lengthy description is necessary, for there are no trees in 

 the state with which they can be confused. As in the 

 Willow Family, the flowers are borne in separate clusters, 

 but in this on the same plant, while in the Willows they 

 are on separate plants. The male flowers are in slender, 

 drooping clusters, while the female form shorter, thicker 

 and erect aments. The numerous fruits in the cluster, 

 when ripe, are small, flattened, one-seeded nutlets with a 

 small, thin wing at either side. 



7. BIRCH. 



(Betula] 



Our Birches are slender trees with slender, limber 

 branches and rather small leaves; the seed-like nutlets dis- 

 tinctly winged. The two species are easily separated by 

 the bark alone. 



(1) PAPER BIRCH. 



(Betula papyrifera Marsh) 



Description. Bark white, smooth, on young branches often with nu- 

 merous dots, peeling readily into thin, paper-like layers, hence the name: 

 leaves ovate, small, toothed on the margins. 



This species in northern and eastern America be- 



