334 THE COTTONWOODS 



difference in character of the wood is, no doubt, caused by 

 difference in soil, moisture, or climatic condition, or all of 

 these features which affect all species of trees. 



Its best development is in the valleys of the Mississippi 

 and Missouri nvers and their eastern tributaries, where 

 it may be seen with a stem one hundred feet high and from 

 six to eight feet in diameter. East of the Appalachian 

 Mountains it is less vigorous, smaller in size, and shorter- 

 lived, although trees eighty feet in height, with a diameter 

 of quite three feet, are not at all uncommon. It grows most 

 rapidly in early life and soon becomes a tree large enough 

 for commercial purposes. Its most vigorous growth is in 

 moist soils along low-bank streams, at the moist bases of 

 hills and mountains, and on the borders of swamps ; ground 

 can be too wet for it, however. It will grow quite readily 

 on poor, dry soils, if not very dry, but it there shows symp- 

 toms of failure quite early in life. It does not grow vig- 

 orously on sandy plains or on dry mountain-tops or on their 

 sterile and dry sides. Ground rather wet for cultivation is 

 well adapted to it. In situations at all suited, it is a very 

 rapid grower, and not much given to developing large 

 limbs, wherein it widely differs from its half-brother the 

 Balm of Gilead, a species which should not be mistaken 

 for it. It is light-demanding and any crowding by other 

 trees will kill off its lower branches. In fact, they will die 

 in a few years from its own shade, even when grown in the 

 open. Its natural habit is to send up a tall, straight stem 

 with a moderate amount of small limbs. But few of our 

 native broadleaf trees will grow as tall in the open. It is 

 shallow rooted, even when growing on moderately rich and 

 moist soil. 



The wood is soft, weak, and with somewhat contorted 

 fibre. It is coarse-grained, difficult to season, with a strong 

 tendency to warp, and shrinks greatly when drying. The 

 heartwood is dark brown, with a very thick and nearly 

 white sapwood. There is little difference between spring 

 and summer wood. It is used for rough lumber, such as 



