TREES, SHRUBS, AND FORESTS 371 



and extending its control over an ever-increasing forest area. 

 The extent to which this policy is being carried out by our 

 national government is indicated by the following data. " On 

 June 30, 1917, there were 147 national forests with a total of 

 155,166,619 acres," yielding an annual income of $3,500,000. 

 On the above date the government employed in this work between 

 three and four thousand men, including forest supervisors and 

 rangers, lumbermen, sealers, planters, and clerks. These various 

 officers are distributed to the different national forests in the pro- 

 portion necessitated by the labor to be performed. They have 

 a great variety of work, including the prevention and control of 

 forest fires, the scientific cutting and marketing of timber, the 

 control of grazing privileges, and the replanting of depleted 

 forests. This mere enumeration of the extent, use, and control 

 of the national forests of the United States is all that can be 

 attempted in an elementary textbook of botany, but every student 

 should acquaint himself with this great industry of our national 

 government, which means so much to the present and future 

 prosperity of our country. 



REPRESENTATIVE GROUPS OF FOREST TREES 



The trees which comprise the forests of the United States 

 belong to the gymnosperms, or naked-seeded plants, represented 

 by the pines and the spruces, and to the angiosperms with a 

 closed pistil, represented by the elm, oak, and maple. In the 

 following species, selected from these two great tree groups, 

 both the economic and the biological features will be considered 

 as concrete illustrations of the importance and interest attached 

 to forest and ornamental trees. 



GYMNOSPERMS (EVERGREENS) 

 THE SPRUCES (PiCEA) 



Habitat and habit. The spruces form an important part of the 

 great coniferous (cone-bearing) and mixed forests of the north- 

 eastern portion of the United States, the Appalachian region, the 



