Page:Popular Science Monthly Volume 68.djvu/216

212. Our soils and climate are almost everywhere well adapted to its growth, its abundant seeds germinate readily, and it responds promptly to the forester's care. The danger of failure in growing this tree for economic uses lies, not in the character of the tree nor in that of our soils or climate, but in the persistent attacks of destructive insects which are natives of the same region with the tree, which follow it in its geographical distribution, and which presently will be further referred to.

There are two North American trees which bear the popular name of locust, the one already mentioned and the honey locust, Gleditschia triacanthus; but it is only the black locust that is referred to in these remarks. This tree originally was known only in that region which lies east of the Allegheny Mountains and between New York and Louisiana. By natural dispersion and artificial propagation, however, it has grown for many years more or less commonly, but for the most part unthriftily, in nearly all the eastern half of the United States, as well as in other parts of North America. Early after its first discovery its seeds were carried to other countries, where the tree was successfully progagated from them. In Europe, especially, where its American insect despoilers never have been introduced, where the indigenous insects never molest it, and where it readily adapts itself to the local climatic and terreous conditions, it has always grown thriftily and symmetrically, reaching a maximum size comparable with that of the oaks. Being there esteemed as an ornamental tree, it is often grown in public parks, and it is also much cultivated in preserved forests for its valuable wood.

This European experience with the black locust tree well illustrates its extraordinary vigor and its ability to reach full maturity of growth under a wide diversity of conditions of soil and climate. Its completely successful growth to trees of medium size in formerly isolated North American districts west of its native regional habitat, and its persistent struggle for existence against its insect despoilers wherever it has been established in our country show that our soil and climate are entirely favorable to its growth and that it is only accessory, but dominant, conditions that are unfavorable. These accessory conditions are now known to be the result of ravages upon the living parts of the tree by the insects referred to. Indeed this tree presents the remarkable case of a strong arboreal species doomed on its native ground and in contiguous regions, to a constant state of suppression of its natural development, and even to local extermination, by insect despoilers which are natives of the same region with the tree and wholly dependent upon it for their own existence. There is no other North American tree, perhaps, excepting the common mezquite of our southwestern states and Mexico, which is so disastrously damaged in its growing condition by indigenous insects as is the black locust, and both of these trees