4 AMERICAN FOREST TREES 



are not agreed upon among scientific men who mention or describe them. 

 The forests of the United States contain more than five hundred 

 kinds of trees, ranging in size from the California sequoias, which 

 attain diameters of twenty feet or more and heights exceeding two 

 hundred, down to indefinite but very small dimensions. The separating 

 line between trees and shrubs is not determined by size alone. In a 

 general way, shrubs may be considered smaller than trees, but a seedling 

 tree, no matter how small, is not properly called a shrub. It is custom- 

 ary, not only among botanists, but also among persons who do not 

 usually recognize exact scientific terms and distinctions, to apply the 

 name tree to all woody plants which produce naturally in their native 

 habitat one main, erect stem, bearing a definite crown, no matter what 

 size they may attain. 



The commercial timbers of this country are divided into two classes, 

 hardwoods and softwoods. The division is for convenience, and is 

 sanctioned by custom, but it is not based on the actual hardness and 

 softness of the different woods. The division has, however, a scientific 

 basis founded on the mechanical structures of the two classes of woods, 

 and there is little disagreement among either those who use forest 

 products or manufacture them, or those who investigate the actual 

 structure of the woods themselves, as to which belong in the hardwood 

 and which in the softwood class. 



Softwoods The needleleaf species, represented by pines, hem- 

 locks, firs, cedars, cypresses, spruces, larches, sequoias, and yews, are 

 softwoods. The classification of evergreens as softwoods is erroneous, 

 because all softwoods are not evergreen, and all evergreens are not 

 softwoods. Larches and the southern cypress shed their leaves yearly. 

 Most other softwoods drop only a portion of their foliage each season, 

 and enough is always on the branches to make them evergreen. Soft- 

 woods are commonly called conebearers, and that description fits most 

 of them, but the cedars and yews produce fruit resembling berries rather 

 than cones. Though the needleleaf species are classed as softwoods, 

 there is much variation in the absolute hardness of the wood produced 

 by different species. The white pines are soft, the yews hard, and the 

 other species range between. If there were no other means of separating 

 trees into classes than tests of actual hardness of wood, the line dividing 

 hardwoods from softwoods might be quite different from that now so 

 universally recognized in this country. 



Hard-woods The broad leaf trees are hardwoods. Most, but not all, 

 shed their foliage yearly. It is, therefore, incorrect to classify deciduous 

 trees as hardwoods, since it is not true in all cases, any more than it is 

 true that softwoods are evergreen. Live oaks and American holly are 



