6 4 



WILD FLOWERS AND TREES OF COLORADO 



ia. Bark of trunk brownish-gray-; fertile catkins about 15 mm. (f in.) long. 



Betula fontinalis Sarg. 

 "Canyon Birch" 



ib. Bark of trunk pale gray or light brownish; fertile catkins about 30 mm. (it in.) long. 



Betula andrewsii A. Nels. 

 "Andrews' Birch" 



Fig. 51. — Canyon Birch (Betula jontinalis). X J 



Genus 9. ALNUS, Alder 



This genus is represented by a single species, a tree or shrub growing 

 in clumps along streams. Leaves broadly ovate, doubly toothed. 



Alnus tenuifolia Nutt. 

 "Alder" 



