TREES AND THEIE VALUE FOE PLANTING 79 



naturally slow, but the rate varies with the conditions of the 

 soil. It takes from i to 15 years to grow an inch in diameter. 

 The height growth does not exceed a foot a year. The wood 

 is light, soft and of compact grain. It will take a high pohsh. 

 The wood is very durable, which makes it a valuable tree for 

 fence posts, poles, chests and railroad ties. The wood is used 

 in the manufacture of lead pencils. Its dense crown makes 

 it a good tree to plant for windbreaks on the Plains. It is 

 reproduced only by seed. Usually it takes two years for 

 germination. The seed should be collected when ripe, soaked 

 in warm water for several hours and stratified in moist sand 

 and planted in the fall, a year from the time they were gath- 

 ered, or kept until the following spring. They are difficult 

 to grow, owing to the damping off fungus. It will be better 

 to purchase small seedlings from nurserymen and set them 

 out for a year or two before planting. It should be planted 

 with light demanding trees like cottonwood and green ash. 

 It will grow more slowly than these trees and form an under- 

 story shading the ground from the sun. When planted in 

 pure plantations on dry uplands it should be spaced 4 by 4 

 feet apart. On better or more moist soils 4 by 6 or 8 feet is 

 best. It is often injured by fungus diseases and by insects. 



American or White Elm (Ulmus Americana). — The 

 American elm is distributed widely throughout the eastern 

 part of the country east of the Rocky Mountains. It seldom 

 forms a large percentage of the trees in the forest. Mature 

 trees vary from 60 to 120 feet in height and from 2 to 8 

 feet in diameter. It grows best on deep alluvial soil with a 

 constant supply of moisture. It will, however, grow on fairly 

 dry soil. It is considered one of the hardiest trees for Prairie 

 planting, as it is able to endure the greatest extremes of 

 temperature and drought of the treeless west. It is grown 

 throughout its range as an ornamental and shade tree. The 

 wood is moderately strong, coarse grained, difficult to split, 

 not durable and liable to warp and check in drying. In young 



