The tree varies greatly in size. In some remote corners of its immense range it is little more than a shrub, while at its best it may attain a height of 100 feet and a diameter of three or four. Its average size is about that of slippery elm. The bark varies as much in appearance as the tree in size. Sometimes it has the smooth surface and pale bluish-green appearance that suggest the bark of beech; again it is darker and rougher, like the elm. It frequently exhibits the harsh warty bark which is peculiar to the hackberry, and when present it is a pretty safe means of identification. The warts may be conical, oblong, or sharp-pointed, and probably an inch in height. When closely examined, most of them are found to consist of parallel strata of bark which may usually be pulled off without much difficulty. The warts are a decided disadvantage to the tree in some of the low swampy districts of Louisiana where Spanish moss is a pest. This moss (which is not a true moss), is propagated principally by tufts and strands which are carried by wind until they find anchorage among the branches of trees where they increase and multiply at a rapid rate until they finally smother or break down the unfortunate tree which supplied a lodging place. The hackberry’s warts catch and hold every flying strand of moss that touches them, and hundreds, perhaps thousands of pounds of it may accumulate on a single tree. The grayish-green color of the moss often exactly matches the hue of the tree’s bark. The reported annual cut of hackberry lumber in the United States is less than 5,000,000 feet. That can be only a fraction of the total output. Few mills report it separately, but list it as ash. The wood looks more like ash than elm. It is heavy, but only moderately hard and strong. Its color is more yellowish than ash, but the annual rings of growth resemble that wood. The sapwood is thick, and growth is rapid where conditions are favorable.