BUR OAK
(Quercus Macrocarpa)
This splendid oak was named by Michaux, a French traveler and botanist who visited many parts of eastern and southeastern United States more than a century ago. The botanical name macrocarpa, means “large fruit.” The bur oak bears small acorns in the North, and very large ones in the South. They are sometimes two inches long and one and a half inches wide, and “large-fruit” oak is an appropriate name for the tree in the South, but would not be near the northern limit of its range.
It is known in different regions as bur oak, mossy cup oak, overcup oak, scrub oak, and mossy cup white oak. Bur oak is a name suggested by the acorn which has a fringe round the cup like a bur. This is the oak which gave name to James Fenimore Cooper’s book, “Oak Openings” a romance of early days in Michigan. Oak openings were areas where fires had killed the old timber, and a young growth had sprouted from stumps and roots, or had sprung up from seeds buried in the ground beyond the reach of the fire. Some of those tracts were very large, and they were not confined to any one state. They existed in Michigan, Wisconsin, Minnesota, Dakota, and elsewhere. Bur oak, because it is a vigorous species, was able to take possession of such burned areas, to the exclusion of most others.
Few American oaks have a wider range. It extends from Nova Scotia to Manitoba, and in the United States is found in most states east of the Rocky Mountains. It extends farther west and northwest than any other commercial oak of the Atlantic states. In a range of so great geographical extent the bur oak finds it necessary to adapt itself to many kinds of land. It prefers low tracts where water is sufficient but not excessive, but it grows well in more elevated situations, provided the soil is fertile. It is not a poor-land tree. In the primeval forests it attained largest size in Indiana and Illinois. The largest trees were from 150 to 170 feet high and four to seven in diameter. Sizes varied from that extreme down to the other extreme near the outskirts of its range where the growth was stunted. Large quantities of very fine logs have been cut from trunks from two to four feet in diameter, and forty to sixty feet to the limbs.
The leaves of bur oak are from six to twelve inches long, simple and alternate; the petioles are thick with flattened and enlarged bases; the leaves are wedge-shaped at the base, and have from five to seven long, irregular lobes, the terminal one very large and broad. They are dark green in color, and are smooth and shiny above, silvery white and pubescent below. The edge of the leaf is notched somewhat like chestnut, but the teeth or notches are not so sharp.
The twigs are provided with corky wings, or flattened keels of bark, along their sides. Some of the wings are an inch or more wide. They are apt to escape notice when the tree is in leaf, but in the winter the bare twigs look rough and ragged.
The weight of bur oak is approximately the same as white oak, and the two woods are much the same in strength and elasticity. The bands of summerwood are broad and dense, and the springwood is filled with large pores. The medullary rays are broad, but not numerous in comparison with white oak. They are sufficiently conspicuous to show well in quarter-sawing.
Bur oak nearly always goes to market as white oak, or simply as oak, and it is difficult to ascertain all the uses found for it. Some factories which make furniture, finish, vehicles, and other articles that figure in the country’s trade, attempt to identify the woods they use. That is done as carefully in Michigan as anywhere else, though comparatively few of the factories carry out the plan even in that state where many of the best wood-using establishments of the country are located. In a report issued in 1912 which gave statistics collected from more than eight hundred Michigan factories, bur oak received separate consideration. The uses there are doubtless representative, and will hold throughout the country wherever bur oak is fairly abundant. It is listed as baseboards, billiard table rims, bookcases, clay working machines, filing cabinets, furniture, hand sleds, hay balers, interior finish, molding, tinplate boxes, wagon sills, work benches. The amount of wood used in the state was nearly 900,000 feet, according to the reports; but it certainly does not include all. What it does show, however, is that bur oak is one of the substantial woods of that region, and that it possesses properties which fit it for many important places in the country’s industries.
Bur oak contributes to the output of cooper shops. Slack coopers class it with many other hardwoods for the manufacture of barrels for vegetables and various other commodities, while the makers of barrels for liquids put bur oak in with white oak.
The future of bur oak does not promise much after the trees which now remain have been cut. That does not mean that the species will become extinct, for that is improbable; but when the mature trees which developed during two or three hundred years of forest conditions have passed away, there is not much prospect of others being left to grow to the age and size which will make them valuable as lumber. Woodlot owners will not wait much longer than the seventy-five or one hundred years required to grow trees of crosstie size. Railroads pay good prices for this wood, for it lasts well, holds spikes in a satisfactory manner, and is strong and hard. As far as can be seen, bur oak will fare in the future about like white oak; that is, few trees will be left standing long enough to attain large size, because it will pay better to cut them while comparatively small.
California Blue Oak (Quercus douglasii) receives its name from the color of its foliage in spring and early summer in the valleys and on the rolling foothills of central California. Later in the summer, when the dry season is on, the leaves lose some of their blue, on account of age, but more from an accumulation of dust; but even then the form of the tree, from its habit of growing in open formation like an old apple orchard, presents an attractive picture. It is often associated with the valley oak, which is larger and more stately, but the blue oak loses nothing by the contrast. It is occasionally called rock oak, but for what reason is not clear. It is known, too, as mountain white oak, or simply white oak, and as blue oak. Its range covers central California from Mendocino to the Mojave desert, and from the immediate coast inland through the valleys to the Sierras, and upward to an altitude of 4,000 feet where the tree degenerates into a shrub which has neither beauty nor utility. The species reaches its best development in the Salinas valley from twenty to sixty miles from the coast. There the largest trees are found, and also some that have assumed peculiar forms. In positions exposed to the never-ceasing sea winds which sweep up the valleys, the blue oaks lie prone like logs, their tops pointing away from the wind. They grew in that unnatural position, having been pressed flat by the wind since they were seedlings. This oak’s ashen gray bark harmonizes well with the dry summer grass and dull sand and gravel which surround it during the hot period. The branches are often covered with green-gray lichens which somewhat modify the aspect of the tree under close inspection. The leaves are irregular in form. Some closely resemble leaves of the eastern white oak, while others are almost or quite without lobes. During the growing season the acorns are deep green, but when approaching maturity they change to a chestnut-brown. They vary in shape as much as the leaves. Some are almost eggshaped, bulging out above the cup which seems too small; but all of them do not assume that form, but may be short and symmetrical, or very long and slender. Woodpeckers store these acorns in large numbers, and they search out peculiar places for their hoards. A knot hole in the weatherboarding of an old barn, granary, or school house is considered ideal, though when the acorns are so disposed of, they are out of reach of the woodpecker forever. Another method is to peck holes just large enough for an acorn in fence posts or dead tree trunks, and hammer the acorns tightly in, small end first. The surfaces of dead trees are sometimes absolutely covered with such holes, each with its acorn. The woodpecker’s purpose is to wait until the acorns become infested with larvÆ. He has no intention of eating the acorn itself.
California blue oaks range in height from shrubs to trees of ninety feet, with diameters of three or four feet. The average height is about forty-five and the diameter two or less. The trunk frequently divides a few feet from the ground into large limbs. That form excludes the wood from sawmills, and only in rare cases does any of it find its way there. The lumber is of poor quality, brittle, black, and otherwise defective. The sapwood is white and thick. A cubic foot weighs 55.64 pounds, or nearly ten more than eastern white oak. It is weak, and is low in elasticity. The annual rings are often nearly invisible, because the pores are scattered evenly and do not form bands. The medullary rays are broad, in the heart black, in the sapwood white. If the wood were otherwise suitable, pleasing effects might be produced by quarter-sawing, but as far as known, no attempts have been made to do this. Now and then a suitable log might be found. The importance of this oak lies in its fuel value. It rates above white oak in theoretical tests, but it is heavier in ash, and in practice it hardly measures up to white oak. It grows slowly and is destined to disappear as a source of fuel supply. Reproduction has nearly ceased in most parts of its range, due largely to the perseverance of hogs in eating the acorns. Cordwood cutters have stripped the last tree from large areas where much once grew. This oak never forms forests. The trees seldom grow as close together as apple trees in an orchard.
Gambel Oak (Quercus gambelii) was destined by nature to occupy an inferior place in the country’s timber resources. It occupies a region of stunted vegetation among the dry mountains and plateaus of the Southwest, and except where it grows in better situations than usual, it is too small to be properly called a tree. It is at its best among the mountains of southeastern Arizona where it grows in canyons that can maintain a little damp soil. There it occasionally reaches a height of thirty feet and a diameter of a foot or less. In most other parts of its range it is simply a tangled, sprawling thicket of brush, covering the dry, rocky mountain ridges, and along the bases of cliffs. It is found from Colorado to western Texas, and westward into Utah, Nevada, and Arizona. The leaves are small, thick, firm, and hairy, typical of desert foliage which must husband the scant water supply. The acorns are pretty large for a tree so stunted, and they are tempting bait for birds and rodents of the region. The acorns are sweet. If this oak’s reproduction depended on acorns alone it is doubtful if it would hold its ground in the face of perpetual adversity; but its roots send up distorted and stunted sprouts which cover the ground, affording hiding places for the few acorns which escape their hungry enemies. Man puts this oak to few uses. It affords a pretty good class of fuel for camp fires, but cordwood cutters cannot make much out of it. In rare instances frontier ranches use a few of the unshapely poles for corral fences, but only as a case of last resort. The names bestowed upon the tree by those who know it best are uncomplimentary. They call it shin oak, pin oak, scrub oak, mountain oak, and Rocky Mountain oak.
Bur oak leaf and acorn
