American Forest Trees Part 30

BITTER PECAN (_Hicoria texana_) is a Texas species which has not been reported elsewhere. The average size of the tree is from fifteen to twenty-five feet in height and eight to ten inches in diameter; but in rich bottom land, particularly along the Brazos river, specimens sometimes attain a diameter of three feet and a height of 100. The leaves are from ten to twelve inches in length, with from seven to eleven leaflets. The nuts are very bitter, but are of approximately the same size and shape as edible pecans. The sh.e.l.ls are thin and very brittle. The tree's range extends inland 100 or 150 miles from the Texas coast.

NORTH CAROLINA s.h.a.gBARK HICKORY (_Hicoria carolinae-septentrionalis_) is found in the neighboring parts of the four states: North Carolina, Georgia, Tennessee, and Alabama. In the best land this tree is occasionally eighty feet high and two or three in diameter, but when it occurs on dry hillsides its average height is twenty or thirty feet, and its diameter about a foot. The compound leaves are from four to eight inches long, with usually three, but occasionally five leaflets. The sweet nuts are small and brown. The bark separates into thick strips a foot or more in length and three or four inches wide. The rough trunk resembles the northern s.h.a.gbark hickory. The wood is very tough, strong, and hard, the heart light reddish-brown, the thin sapwood nearly white. It is not distinguished from the other hickories in commerce, and it has the same uses when any use is made of it.

[Ill.u.s.tration]

WHITE ELM

[Ill.u.s.tration: WHITE ELM]

WHITE ELM

(_Ulmus Americana_)

Six species of elm occur in the United States, not counting the planer tree as an elm, though lumbermen usually consider it as such.[5] The white elm is the most common, is distributed most widely, and is commercially the most important. More of it is used as lumber, slack cooperage, and other forms of forest products, than all other elms of this country combined. The statistics of sawmill output collected annually by the United States census are not compiled in a way to show the elms separately. All go in as one. The annual lumber cut of elm in the whole country is about 265,000,000 feet, distributed over thirty-four states, with Wisconsin leading, followed in the order named by Michigan, Indiana, Ohio, Missouri, Arkansas, New York, and Minnesota.

In addition to lumber, elm furnishes about 130,000,000 slack cooperage staves yearly.

[5] The elms are white elm (_Ulmus americana_), cork elm (_Ulmus racemosa_), slippery elm (_Ulmus p.u.b.escens_), cedar elm (_Ulmus cra.s.sifolia_), wing elm (_Ulmus alata_), and red elm (_Ulmus serotina_). They are all confined to the region east of the Rocky Mountains.

The elms, taken as a cla.s.s, are much alike. There is more resemblance between the species than between species of oaks or pines, yet some difference exists between elms. This holds not only between different species, but between individuals of the same species. Climate, situation, and soil have much to do with the character of the wood of the same species. So great is the difference at times that fairly good judges of timber are deceived as to the species. A tree growing on dry, rocky soil produces wood quite different from one on rich, deep, well-watered soil. Not only is the wood of one different from that of the other, but the appearances of the standing trees are not alike. The differences may not show in leaves, flowers, and fruit as much as in the shapes and sizes of trees, and the habit of the branches.

White elm is by common consent the type of the genus, the standard by which the other species are measured. It is proper to compare certain properties and characters of other elms with white elm, in order that a general view of all may be had. The dry weights, per cubic foot, of wood are as follows: White elm 40.54 pounds, slippery elm 43.35, cedar elm 45.15, cork elm 45.26, and wing elm 46.69. Figures which show the weight of the southern red elm (_Ulmus serotina_) are not available. White elm is thus shown to be lightest of the group.

Its breaking strength averages 12,158 pounds per cubic inch, under the usual tests by which the strength of woods is determined. Reduced to everyday language that means that 12,158 pounds would just break a white elm stick, 2? inches square, and resting on supports twelve inches apart. That is the meaning of "breaking strength," or "modulus of rupture," as the term is used in engineering text books relating to woods. The following figures for the breaking strength of other elms make comparisons with white elm easy: Cedar elm 11,000; wing elm 11,162; slippery elm 12,342; cork elm (often called rock elm) 15,172. It is shown that two elms are stronger and two weaker than white elm. This wood rates very little below white oak in strength.

The different species of elms vary considerably in stiffness, or the ability to spring back when bent. This factor is expressed by engineers in high figures, is purely technical, and is based on a wood's ability to stretch and regain its former position. The only service which the figures can render to the layman is to furnish a basis for comparing one wood with another. The stiffer a wood, the greater its resistance to an effort to stretch it lengthwise. White elm's measure of stiffness (modulus of elasticity) is 1,070,000 pounds per square inch; wing elm 853,000; cedar elm 981,000; slippery elm 1,318,000; cork elm 1,512,000.

It is shown here, as was shown in the figures representing the strength of the elms, that two species rate above and two below white elm in stiffness.

White elm is known by several names. The color of the bark is responsible for the name gray elm among lumbermen and woodworkers of the Lake States. American elm is a translation of its botanical name, and is neither descriptive nor definitive, because there are other elms as truly American as this one. White elm distinguishes its wood from the redder wood of slippery elm, but it would often be difficult if not impossible to identify the elms, or any one of them, by the color of the wood alone. Some persons who call this elm white doubtless refer to the color of the bark, as is the case with those who speak of it as gray elm. It is known as water elm in several states, but that name is applied indiscriminately to any elm that frequents river banks, as most of them do in some part of their range. It is called rock elm when it is found on stony uplands, and swamp elm on low wet ground. In some parts of the Appalachian mountain ranges it is called astringent elm to distinguish it from slippery elm.

White elm surpa.s.ses the others in extent of range. Its northern boundary stretches from Newfoundland, across Canada to the eastern base of the Rocky Mountains, a distance of nearly 3,000 miles. It runs south through the Atlantic states to Florida, a distance of 1,200 miles or more. Its southwestern limit is in Texas. The area thus bounded is about 2,500,000 square miles. A few other trees have ranges as large, but none much exceed it. It covers so much of America, and is so important in many parts of its range, that it is clearly the leading elm in this country. It is ent.i.tled to first place among elms for other reasons.

It is not easy to give any sure features or characteristics by which the layman may always distinguish this elm from others with which it is a.s.sociated; however, by carefully observing certain features, the ident.i.ty of white elm is generally easy to establish.

The leaves have teeth along the margins like beech and birch. They have straight primary veins running from the midrib to the points of the teeth. Before falling in autumn the leaves turn yellow. The foliage is not very thick, and most of it is near the ends of the limbs. The bloom comes early in the spring, ahead of the leaves, and the seeds are ripe and ready for flight before the leaves are grown. Sometimes the seeds are ripe almost before the leaves are out of the buds. The seeds are oblong, and about the size of a small lentil. The wing entirely surrounds the seed, and is about half an inch long. The flight of elm seeds is an interesting phenomenon. The individual seeds are so small that they are not easily seen as they sail away from the tall tree top but when they go in swarms, in fitful puffs of wind, they are not hard to see. It is chiefly by their fruits that they are known, that is, by the mult.i.tudes of seedlings that appear a few weeks later. If one seedling elm in a thousand should reach maturity, there would be little besides elms in the whole country. They spring up by highways and hedges, in gutters, fields, and even between cobbles and bricks of paved streets; but in a few days they have crowded one another to death, or have perished from other causes, and those which manage to live to maturity do not much more than make up for old trees which perish from natural causes.

The botanist Michaux p.r.o.nounced the white elm "the most magnificent vegetable of the temperate zone." A number of trees are larger, though this reaches great size. Sargent sets the limit of the tree at 120 feet high and eleven feet in trunk diameter. That size is, of course, unusual, but it has been surpa.s.sed at least in height. A tree in Jefferson county, Pennsylvania, was 140 feet high, and although forest grown, it had a spread of crown of seventy-six feet. It was sent to the sawmill where it made 8,820 feet of lumber. That trunk was only five feet in diameter.

Some of the finest forest grown elms in this country have been cut in Michigan. Their trunks were as tall, straight, and shapely as yellow poplars, and their crowns surpa.s.sed those of poplars. It was formerly not unusual for sawlogs to be cut from elm limbs which branched from the trunk fifty or more feet from the ground. The best of the forest grown elm of this country has been cut; but it is still lumbered throughout the whole eastern half of the United States.

The finest elms of this country, and doubtless the finest in the world, are the planted trees in some of the New England villages. The largest of them have been growing for two hundred years, and in many instances they still show the vigor of youth. Trunks six or seven feet through are not uncommon, but the glory of the trees is not alone in the trunks.

Their spread and form of crown are magnificent. The largest are 150 feet across, and some of the splendid branches, rising in parabolic curves, are fully 100 feet long, from the junction with the tree to the tips of the twigs. The most apt comparison for that form of elm is the spray of a fountain. The upward jet of water corresponds to the trunk of the tree; the upward, outward, and downward curves of the spray represent the crown of the elm. Trees which take that form are grown in open ground where sunlight and air reach every side. Forest grown trees are less symmetrical, but even in dense woods, the elm frequently rises clear above the canopy of other trees, and develops the fountain form of crown. The new England street and park elms surpa.s.s those farther west only because they are older. The splendid trunks and crowns are the work of centuries.

[Ill.u.s.tration]

CORK ELM

[Ill.u.s.tration: CORK ELM]

CORK ELM

(_Ulmus Racemosa_)

This tree is called cork elm in Vermont, Ma.s.sachusetts, Rhode Island, New York, New Jersey, Arkansas, Kentucky, Missouri, Wisconsin, Michigan, Iowa, and Ohio; rock elm in Rhode Island, Kentucky, West Virginia, Missouri, Illinois, Wisconsin, Iowa, Michigan, Nebraska; hickory elm in Missouri, Iowa, Illinois, and Indiana; white elm in Ontario; Thomas elm in Tennessee; northern cork-barked elm in Tennessee; corkbark elm, New York; northern cork elm, Vermont; wahoo, Ohio; cliff elm in Wisconsin.

Cork elm is the natural name. It is a descriptive term which a stranger would be apt to apply on seeing the tree for the first time. The bark of the branches, after it has attained an age of three or four years, becomes rough by the growth of ridges and protuberances. This feature is sometimes so prominent that it at once attracts attention, particularly when the branches are bare of leaves; hence the name cork elm.

Lumbermen insist on naming the tree rock elm. They refer to the hardness of the wood, or they may have in mind the dry, stony situations where tough, strong elm grows. The latter is often the case, because the name is applied also to slippery elm and white elm if they grow on stony ground. A wide-spread opinion prevails that wood which grows among rocks is harder, tougher, stronger, and more durable than that produced by deep, fertile soil. It is possible to cite much evidence to support that view, and the case might be considered proved, but for the fact that an equal, or greater amount of evidence, in every way as trustworthy, may be cited on the other side. The strongest hickory, ash, and oak do not come from stony land. It sometimes happens that a species with tough, strong wood, is found on rocks, but it is not tough because it is there, but in spite of being there.

The name cliff elm which this tree bears in Wisconsin is but another form of the name rock elm, and clearly has reference to the situation where the tree grows in that part of the country. Hickory elm, on the other hand, a name applied to this tree much farther south, is a recognition of the wood's toughness.

In some particulars it does not fall much below hickory in toughness, but is not as strong, elastic, or capable of as smooth polish. The latter property is one of the recommendations of hickory when used for handles. It is very smooth to the touch; cork elm is less so. In the northern woods, elm ax handles are in use, and some axmen prefer them to hickory. Such is probably the case when the best cork elm and a medium or poor quality of hickory are in compet.i.tion.

The fibers of cork elm are interlaced, rendering the splitting of the wood difficult. For uses in which that is a desirable property, it is preferable to hickory. It is better for hubs for large wagons, and that is a very important use for this elm.

The wood of all the elms is ring-porous; that is, the springwood, or inner part of the annual ring, consists of one or more rows of large ducts. The summerwood contains pores in large numbers, but they are small, and are usually arranged in short curved lines. The medullary rays are not prominent in the wood of any of the elms, and quarter-sawing adds no beauty to the lumber. The wood is practically without figure, on account of either annual rings or medullary rays; but it may be stained, polished, and made very attractive. That is done oftener with white elm than with any other.

The strength of cork elm created demand for it in boat building at an early day. The tree is and always was scarce in the vicinity of the Atlantic sea board, and the earliest boat builders seem not to have been acquainted with the wood. It was most abundant in the forests of Michigan, though it extended westward to Nebraska. It was plentiful in the province of Ontario, and the timbers from that region acquainted English shipbuilders with the merits of the wood. They sent contractors into Michigan to buy cork elm, long before the other hardwoods of that region had attracted the attention of the outside world. The most convenient supplies of cork elm on the Lower Michigan peninsula thus pa.s.sed through Canada to ship yards on the other side of the sea. The wood is reputed to be more durable than any of the other elms.

It is generally understood that the country's supply of cork elm is running short, but there are no statistics which show how much is left or how much has been cut. It is doubtful if the original forests, including the whole country, had one tree of cork elm to twenty of white elm. The average size of cork elm is sixty feet high and two in diameter. The trunks are well shaped, if forest grown. They develop small crowns in proportion to the size of trunks; and the crowns are less graceful than those of white elm--lacking the long, sweeping curves of the latter. The general contour of the tree has been compared to white oak.

Cork elm grows well when planted on the Pacific coast, in environments quite different from its native habitat. In the forest it increases in size slowly; when planted it makes much better headway. It has a disagreeable habit of sprouting which puts it out of favor as a park tree.

The wood of the different elms is largely used for manufacturing purposes. They are sometimes kept separate, but generally not. The particular place where cork elm is preferred is in the manufacture of vehicles and boats, but it is by no means confined to those commodities.

The state of Michigan alone sends 50,000,000 feet of elm a year to its factories to be converted into articles of general utility. Furniture makers take over 2,000,000 feet of it, though elm is not cla.s.sed as a furniture wood. In certain places it is superior to almost every other wood. No matter how discolored it becomes by weathering and the acc.u.mulation of foreign substances, a vigorous application of soap, water, and a scrubbing brush will whiten it. It is liked in certain parts of refrigerators which need constant scrubbing. Elm to the extent of 8,000,000 feet goes into refrigerators in Michigan alone.

The strength and toughness of elm make it suitable for frames of tables.

When thus used, it is generally out of sight, but not infrequently it is made into table legs as well as frames. Statistics show that more than a million feet are manufactured yearly into handles in Michigan alone. All three of the northern elms--white, cork, and slippery--are listed in the handle industry.

Many millions of feet of elm are yearly converted into automobile stock--3,000,000 in Michigan. Horse-drawn vehicles take more. The most common place for it is the hub, but it serves also as shafts, poles, reaches, and even as spokes for wagons of the largest size.

The important place in the slack cooperage industry held by elm is well known. It is a flour barrel wood, but is employed for barrels of many other kinds. It stands high as veneer, not the kind of which the visible parts of furniture are made, but the invisible interior, built up of veneer sheets glued together. A similar kind of veneer forms the boxes or frames of trunks--the part to be covered by metal, leather, or cloth.

The slats which strengthen the outside of trunks are frequently of elm.

This wood is not in favor for one important purpose, hardwood distillation. It has escaped pretty generally also from being employed as a farm material, on account of its poor lasting qualities. Some slippery elm was mauled into fence rails in the pioneer days of Ohio, Indiana, and southern Michigan, but that was only because it was plentiful and convenient. Cork elm probably never made a fence rail, because it is so unwedgeable that no rail splitter would have anything to do with it. At the best, it is but a temporary makeshift as fence posts, but by applying creosote and other preservative treatments to lessen decay, it measures up with most other post woods.