The pines have smooth, straight, solid trunks, usually destitute of branches for many feet from the ground. There are needle-shaped, more or less cylindrical, evergreen leaves from one to many inches in length, gathered in clusters of two, three, or five, their number and the fact that they are thus clustered being important bases of classification. There are also cones of woody overlapping scales. They reproduce with difficulty,[72] and mature so slowly that ultimate survival of modern conditions must probably be as cultivated trees. Thirty-nine of the seventy known species of pine are found in the United States. These with their woods are separated into two groups known as _hard_ and _soft_ pines. The Dantzic or Northern pine (_Pinus silvestris_) is the principal European species. [p131] FOOTNOTE [Footnote 72: The roots of most species die with cutting of trees. There is no power of producing new shoots. (The pitch pine (_Pinus rigida_) is an exception to this rule.) Seeds also have short-lived vitality. Trees are easily raised from fresh seeds.] SOFT PINE. Soft pine is soft, clean, light, uniform, easily worked, not strong, free from knots and resins, and obtainable in large and perfect pieces. The wood is whitish and the yearly rings are not pronounced. The supply is divided, as obtained from the white pine on the one hand, and from the sugar-pine and all other species on the other. White pine (_Pinus strobus_) grows in the north, central, and eastern United States and was formerly the important tree of North America. It emphasized the forest industries of Maine and of Michigan, and methods connected with harvesting it have influenced logging practices in many fields. It was long the only softwood seriously considered by Northern lumbermen. Thirty per cent of the sawn timber and lumber used in this country in 1899 was drawn from this species.[73] White pine is diminishing so rapidly as to be already practically unobtainable in many places. The Sugar Pine (_Pinus lambertiana_) of the Western States is a tree growing at high elevations and is so large as to take rank with the redwoods and other of the world's greatest trees. Some material is derived from the Western white pine (_Pinus flexilis_) and one or more minor species. Sugar pine resembles, but is not as desirable as, white pine. The sweetish exudations from this tree are sometimes used in medicine. [p132] FOOTNOTES [Footnote 73: Roth, U. S. Forestry Bul. No. 22, p. 73.] "White Pine Timber Supplies." U. S. S. Doc. 55-1, Vol. IV. HARD PINE. Hard pine differs from soft pine in that it is hard, resinous, heavy, harder to work, and very strong. It also is obtainable in large pieces. The orange-yellow wood is more or less figured. The annual deposits are pronounced and are separated into two sharply divided rings. The supply is chiefly derived from the longleaf, shortleaf, Cuban, and loblolly pines of the South Atlantic States.