Seven hemlocks are known in the world, four of them in America. Two of these are in the East, two in the West. The eastern species are the Canadian and Carolinian. The former is _Tsuga canadensis_, the latter _Tsuga caroliniana_. The western species are, mountain hemlock (_Tsuga mertensiana_), and western hemlock (_Tsuga heterophylla_). The word _tsuga_ is Japanese and means hemlock.
The hemlock lumber in eastern markets is practically all from one species, which is known as hemlock in Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, Pennsylvania, Delaware, Virginia, North Carolina, South Carolina, Kentucky, Wisconsin, Michigan, Minnesota, Ohio, Ontario. In Vermont, Rhode Island, New York, Pennsylvania, New Jersey, West Virginia, North Carolina, South Carolina; in England it is called hemlock spruce; spruce tree in Pennsylvania and West Virginia; spruce pine in Pennsylvania, Delaware, Virginia, North Carolina, Georgia; to the New York Indians it was known as oh-neh-tah, which being interpreted means “greens on the stick.”
The range of hemlock extends east and west more than fifteen hundred miles, from Nova Scotia to western Wisconsin; south to Delaware and southern Michigan, and along the Appalachian mountains to northern Alabama and Georgia. The original quantity of timber was enormous, for large areas were covered with dense stands. The largest trees are found near the southern part of its range, among the mountains of Tennessee and North Carolina; but the bulk of the timber has always been in the North. It thrives best in well drained soil, but it likes cool situations and often develops dense forests on northern slopes or in deep ravines; but it maintains a foothold on ridges, on the banks of streams, and around the borders of swamps.
The cones are very small, about a half inch in length, growing singly from the lower side of the branchlet. Their scales are rounded and thin, light brown in color. The seeds are winged and even when ripe the cones do not spread apart perceptibly. The seeds escape, however, slowly during the winter following their maturity. They are very small, and their wings distribute them a hundred feet or more. The seeds germinate best on leaf mold, but the seedling takes several years to thrust its roots deep into the mineral soil. During that time, growth is very slow. A seedling five years old may not exceed five inches in height; but when its roots have developed, growth is fairly rapid. The distribution of seeds is often facilitated by the activities of red squirrels, and perhaps other small mammals, which climb the trees in winter and tear the cones apart to get at the seeds. Many of the seeds are devoured, but more escape and fly away on the winter winds.