SWEET BIRCH
(Betula Lenta)

Ten species of birch occur in the United States, including Alaska. Six are eastern and four western.[8] Sweet birch is known by that name in many localities, but in others as black birch, cherry birch, river birch, mahogany birch, and mountain mahogany. Its range extends from Newfoundland to northwestern Ontario, south to southern Indiana, Kentucky, and along the Appalachian mountains to Tennessee and North Carolina. Probably the best development of the species is found in the Adirondack region of northern New York, in the northern peninsula of Michigan, through southern Ontario, and along the mountain ranges southward through Pennsylvania and West Virginia.

It attains a height of seventy or eighty feet, and a diameter of two or three. It prefers deep, moist, rich soil, but will grow in comparatively dry, rocky ground. Its seeds are produced in large numbers and are scattered by the wind a hundred feet or more from the parent tree. They lack the wing power and the buoyancy of the seeds of some of the other birches, but they manage to get themselves sown in sufficient numbers, and their powers of germination are good.

The young seedling comes into existence with smooth bark, but it does not keep it through life. As age increases, the bark becomes rough and black. It is not shed in papery rolls and flakes as is the bark of river birch, yellow birch, and paper birch, with which it is associated in some parts of its range. It is generally an easy tree to identify and the black, rough bark is generally a sufficient guide.

The sweet birch is tapped like sugar maple, but not for the same purpose or to the same extent—only an occasional tree. Immense quantities of sap will flow from it during the two or three weeks when the buds are swelling in the spring. It is said that as much as two tons has been known to flow from a medium sized birch in a single season. The sap is made into a beer which has some commercial value, but is chiefly used locally. One of the ways of making it, employed by farmers and woodsmen, is to jug the sap, put in a handful of shelled corn, and let fermentation do the rest.

A substance known in commerce as oil of wintergreen is procured almost exclusively from this birch, though occasionally it is made from the small wintergreen plant (Gaultheria procumbens). The product is manufactured in very crude stills made by mountaineers in Pennsylvania and southward along the mountains where sweet birch is abundant. Frequently the woodsman’s whole family go into the business, chopping down birch bushes and hacking them with hatchets into chips of the desired sizes. The oil is extracted from the hogged mass by a steaming and roasting process. It is sold by the quart to country storekeepers who ship it to wholesale druggists where it is refined and used to flavor candy, medicine, and drugs. The woodsman who manufactures the oil prefers young birches from half an inch to two or three inches in diameter, and he usually procures them in old logging grounds where seedlings have sprung up. It is said that on an average one hundred small birch trees are destroyed for each quart of oil that goes to market. It is a process wasteful in the extreme.

In the open ground, sweet birch develops a full crown, short trunk, abundance of limbs, with numerous slender, graceful twigs and small branches. Its leaves form a dense mass, and they are so free from attacks by insects and worms that diseased foliage is unusual. That cannot be said, however, of the trunk. It is not particularly liable to disease, but many old trees show the results of decay. It is of slow growth, and a small tree may be much older than its size indicates. The sapwood is generally thick, heartwood forms slowly, and the contrast in color between sap and heart is strong.

The wood of sweet birch had few uses in early times, except fuel. The pioneer sawmill had little to do with it. Lumber was hard to saw and was seasoned with difficulty. Its tendency to warp was too great a tax on the lumberman’s patience and ingenuity. The only way he could hold it straight was to cob a few layers in the bottom of a pile, and stack thousands of feet of other lumber on top, and leave it a year or two. That was generally too much trouble, particularly when the wood had slow sale, and the price was low. Birch reached market in large quantities only when modern mills and improved drykilns came into existence.

The wood is heavy, strong, hard, in color dark brown tinged with red. The light brown or yellow sapwood generally makes up seventy or eighty annual rings. The difference between springwood and that of the later season is not clearly marked, and consequently the rings are often indistinct. The wood is very porous, and the pores are diffused through all parts of the ring. They are too small to be seen with the naked eye, except under the most favorable conditions. The medullary rays are numerous but so small that they appear on the quartered wood merely as a gloss, which, however, gives the surface a rich appearance.

Forms known as curly and wavy birch are highly esteemed. They are accidents of growth, well developed in birch, and occurring in several other woods. Difficulties are encountered in assigning sweet birch its individual place in the industrial world. As a tree it is well known, but that is not the case when its lumber goes to market. The sweet birch log goes into the sawmill, but when the lumber goes out at the other end of the mill, it is often simply birch having lost the adjective “sweet” somewhere in the operation. The reason is that sweet birch and yellow birch, quite distinct in the forest, are often mixed and become one, to all intents and purposes, when they reach the market. That is not always the case, but it frequently is. Something depends on the region. The yellow birch’s range is more extensive, and in areas where it is abundant, and sweet birch is not, it prevails in the lumber markets. But south and southeast of the great lakes, as well as in the northeastern part of the country, the two species mingle, and they are apt to go to market simply as birch. The woods may be distinguished by a microscopic examination, but the ordinary observer would make many mistakes if he attempted to tell one from the other in the lumber yard.

The two woods are different in several physical properties. Both are heavy, but sweet birch weighs 47.47 pounds per cubic foot, while yellow birch weighs only 40.84 pounds, according to tests averaged by Sargent. Yellow birch rates a little above the other in breaking strength. Both are very stiff, but yellow birch rates superior. In most respects the two woods are put to similar uses—flooring, interior finish, furniture—but for some purposes sweet birch is preferred. It is substituted oftener for cherry and mahogany, and for that reason is known as cherry birch or mahogany birch. Its color makes the substitution easy, and the appearance of the grain, with a little doctoring with stains and fillers, helps in the deception. The buyer may be deceived as to the exact kind of wood he is getting, but he is not cheated in the quality. Birch is substituted where strength is required, as in the rails of beds, the frames of sofas, davenports, large chairs, and certain parts of large musical instruments. It is much stronger, and fully as hard as cherry or mahogany, and as its appearance is so much like them, the article is actually better on account of the substitution. Sweet birch is largely employed for various parts of vehicle manufacture, particularly for wagon hubs and frames of automobiles. It is also much used in the manufacture of sleds, boats, and handles.

The demand is heavy and the supply is diminishing. The tree is of such slow growth that few timber owners will be inclined to wait for a second crop, after the old trees have been cut, since 150 years are necessary under forest conditions to produce a merchantable tree.