THE BmCIIES 87 



Knowlton's Ironwood 



0. Knowlloniy Co v. 



Knowlton's iron wood is found nowhere but in a thi'^'^ 

 grove on the southern slope of the canyon of the Colorado 

 in Arizona, about seventy miles north of Flagstaff. Here 

 these trees are numerous, crouching under oaks, their 

 twisted branches ending in drooping twigs, bearing the 

 characteristic pale green hops in autumn, small oval leaves, 

 and the catkin flowers in spring. Such a restricted dis- 

 tribution for a distinct species of trees is unmatched in the 

 annals of botany. 



THE BmCHES 



Grace and gentility of appearance are attributes of this 

 most interesting, attractive, and valuable family of trees. 

 Shabby gentility, one may insist, tliinking of the untidy, 

 frayed-out edges that adorn the silky outer bark of almost 

 every birch tree in the woods. (See illustration, page 102.) 

 Not one of them, however, but lends a note of cheerfulness 

 to the landscape. There is beauty and daintiness in leaf, 

 flower, and winged seed, and despite the inferiority of most 

 birch wood, the history of the family is a long story of use- 

 fulness to the human race. 



About thirty species of birches grow in the Northern 

 Hemisphere, ten of them are North American. The white 

 birch of Europe extends across the northern half of Asia, 

 and is cultivated in delicate cut-leaved and weeping forms, 

 as a lawn and park tree in this country. 



