Nut Trees - The Oaks
( Originally Published 1927 )
This is the great family of the cup-bearers, whose fruit, the acorn, is borne in a scaly cup that never breaks into quarters, as does the husk that holds a chestnut, beechnut, or hickory nut. All oak trees bear acorns as soon as they come to fruiting age. This is the sign by which they are known the world over. Seldom is a full-grown oak without its little insignia, for the cups cling after the nut falls, and one grand division of the family requires two seasons to mature its fruit. For this reason, half-grown acorns are seen on the twigs after the ripe ones fall.
We cannot say of oak trees that they all have sturdy trunks, rough bark, and gnarled limbs, for not all of them have these characteristics. But there is a certain likeness in oak leaves. They are simple, five-ranked, generally oval, and the margins are generally cut into lobes by deep or shallow bays. Most oak leaves have Ieathery texture, strong veins, and short petioles. They are leaves that outlast the summer, and sometimes persist until spring growth unseats the stalks; sometimes, as in the "live oaks," they hang on three to five years.
The twigs of oak trees are more or less distinctly five-angled, and the winter buds cluster at the ends. This insures a group of young shoots, crowded with leaves, on the ends of branches, and a dense outer dome of foliage on the tree.
Nearly three hundred distinct species of oaks are recognized by botanists, and the list is growing. New species are in the making. For instance, a white oak and a bur oak grow near enough for the wind to "cross-fertilize" their pistillate flowers. The acorns of such mixed parent-age produce trees that differ from both parents, yet reveal characteristics of both. They are "hybrids," and may be called new varieties of either parent. Other species of oak are intercrossing by the same process—the interchange of pollen at the time of blossoming. This proves that the oak family is young, compared with many other families, whose members are too distantly related to intercross.
Though geologically young, the oak family is one of the most important, furnishing timber of superior strength and durability for bridge-building, ship-building, and other construction work. Tanning has depended largely upon oak bark. As fuel, all oak trees are valuable.
Fifty species of oak are native to North American forests. Twice as many grow east of the Rocky Mountains as west of the Great Divide. No species naturally passes this barrier. The temperate zone species extend southward into tropical regions, by keeping to high altitudes. Thus we find American oaks in the Andes and Colombia; Asiatic species occur in the Indian Archipelago. No Old World species is native to America. Each continent has its own.
East of the Rocky Mountains the oaks hold a place of preëminence among broad-leaved trees. They are trees of large size, and they often attain great age. They are beautiful trees, and therefore highly valued for ornamental planting. This has led to the introduction of oaks from other countries. We have set European, Japanese, and Siberian oaks in our finest parks. Europe has borrowed from our woods the red oak and many others. All countries are richer by this horticultural exchange of trees.
Our native oaks fall into two groups : the annual-fruiting and the biennial-fruiting species. The first group matures its acorns in a single season; the second requires two seasons. It happens that annuals have leaves with rounded lobes, while biennials have leaves with lobes that end in angles and bristly tips. The bark of the annual trees is generally pale; that of the biennials, dark. Hence the white oak group and the black oak group may be easily distinguished at a glance, by the bark, the leaf, and the acorn crop.
THE WHITE OAK GROUP
The White Oak
Quercus alba, Linn.
The white oak has no rival for first place in the esteem of tree-lover and lumberman. Its broad, rounded dome, sturdy trunk, and strong arms (see illustration, page 88), and its wide-ranging roots enable a solitary tree to resist storms that destroy or maim other kinds. Strength and tenacity in the fibre of root and branch make it possible for individuals to live to a great age, far beyond the two centuries required to bring it to maturity. Such trees stir within us a feeling of reverence and patriotism. They are patriarchs whose struggles typify the pioneer's indomitable resistance to forces that destroyed all but the strong.
White oak trees in the forest grow tall, lose their lower branches early, and lift but a small head to the sun. The logs, quarter-sawed, reveal the broad, gleaming "mirrors that make a white oak table beautiful. The botanist calls these the medullary rays—thin, irregular plates of tissue-building cells, that extend out from the central pith, sometimes quite to the sap-wood, crowding between the wood fibres, which in the heart-wood are no longer alive. A slab will show only an edge of these mirrors. But any section from bark to pith will reveal them.
The pale brown wood of the white oak distinctly shows the narrow rings of annual growth. Each season begins with a coarse, porous band of "spring wood," followed by a narrower band of fine, close-grained "summer wood." White oak is streaked with irregular, dark lines. These are the porous lines of spring wood, discolored by foreign matter. Count them, allow a year for each, and you know how long one white oak tree required to make an inch of wood.
The supreme moment in the white oak's year comes in spring, when the gray old tree wakes, the buds swell and cast off their brown scales, and the young leaves appear. The tree is veiled, not with a garment of green, but with a mist of rose and silver, each twig hung with soft limp velvety leaves, red-lined, and covered with a close mat of silky hairs. It is a spectacle that seems unreal, because it is so lovely and gone so soon. The protecting hairs and pigments disappear, and the green leafage takes its place, brightened by the yellow tassels of the stamen flowers, and the growing season is on.
In autumn the pale-lined leaves of the white oak turn slowly to sombre violet and dull purplish tones. Clinging there, after the acorns have all fallen and been gathered by squirrels, the foliage fades into the gray of the bark and may persist until spring growth sets in.
The Bur Oak
Q. macrocarpa, Michx.
The bur oak is called the mossy-cup on account of the loose, fringed scales about the rim of the cup that holds the large acorn—largest in the whole oak family. Often the nut is completely enclosed by the cup; often it is small. This variable fruit is sweet, and it is the winter store of many furry wood-folk.
The leaf has the rounded lobing of the family, with the special peculiarity of being almost cut in two by a pair of deep and wide opposite sinuses, between the broad middle, and the narrow, tapering base. Not all leaves show this odd form, but it is the prevailing pattern. The dark green blade has a pale, fuzzy lining, that lasts until the leaves turn brown and yellow.
The bur oak is a rugged, ragged tree, compared with the white oak. Its irregular form is picturesque, its wayward limbs are clothed in a loose garment of untidy, half-shed bark. The twigs are roughened with broad, corky wings.
The trunk is brownish, with loosened flakes of gray, separated by shallow fissures.
The wood is classed with white oak, though darker in color. It has the same ornamental mirrors, dear to the heart of the cabinet-maker. It serves all the purposes for which a tough, strong, durable wood is needed.
The range of the species is from Nova Scotia to Montana, and it grows in large tracts from Winnipeg to Texas, doing well in the arid soil of western Nebraska and Dakota. Suckers from the roots spread these trees till they form the "oak openings" of the bluffs of the Missouri and other streams of Iowa and Minnesota. In Kansas it is the commonest oak tree. The largest trees of this species grow in rich bottom lands in the Ohio Valley.
The Post Oak Q. minor, Sarg.
The post oak has wood that is noted for its durability when placed in contact with the soil. It is in demand for fence posts, railroad ties, and for casks and boat timbers. "Iron oak" is a name that refers to the qualities of the wood. "Knees" of post oak used to be especially in demand.
In the Mississippi Basin this tree attains its largest size and greatest abundance on gravelly uplands. It is the commonest oak of central Texas, on the sandy plains and limestone hills. Farther north, it is more rare and smaller, becoming an undersized oak in New York and westward to Kansas.
In winter the post oak keeps its cloak of harsh-feeling, thick, coarse-veined leaves. Tough fibres fasten them to the twigs. In summer the foliage mass is almost black, with gray leaf-linings. The lobes and sinuses are large and squarish, the blades four or five inches long. The limbs, tortuous, horizontal, form a dense head.
The Chestnut Oak
Q. Prinus, Linn.
The chestnut oak has many nicknames and all are descriptive. Its leaves are similar in outline and size to those of the chestnut. The margin is coarsely toothed, not lobed, like the typical oak leaf. "Tanbark oak" refers to the rich store of tannin in the bark, which makes this species the victim of the bark-peeler for the tanneries wherever it grows. "Rock chestnut oak" is a title that lumbermen have given to the oak with exceptionally hard wood, heavy and durable in soil, adapted for railroad ties, posts, and the like.
Unlike other white oaks, the bark of this tree is dark in color and deeply fissured. Without a look at the leaves, one might call it a black oak.
The centre of distribution for this species seems to be the foothill country of the Appalachian Mountains, in Tennessee and North Carolina. Here it predominates, and grows to its largest size. From Maine to Georgia it chooses rocky, dry uplands, grows vigorously and rapidly, and its acorns often sprout before falling from the cup!
The chestnut oak is one of the most desirable kinds of trees to plant in parks. It is symmetrical, with handsome bark and foliage. The leaves turn yellow and keep their fine texture through the season. The acorn is one of the handsomest and largest, and squirrels are delighted with its sweet kernel.
The Mississippi Valley Chestnut Oak
Q. acuminata, Sarg.
In the Mississippi Valley the chestnut oak is Q. acuminata, Sarg., with a more slender and more finely-toothed leaf that bears a very close resemblance to that of the chestnut. The foliage mass is brilliant, yellow-green, each leaf with a pale lining, and hung on a flexible stem. "Yellow oak" is another name, earned again when in autumn the leaves turn to orange shades mingled with red.
On the Wabash River banks these trees surpass one hundred feet in height and three feet in diameter. The base of the trunk is often buttressed. Back from the rich bottom lands, on limestone and flinty ridges, where water is scarce, these trees are stunted. In parks they are handsome, and very desirable. The bark is silvery white, tinged with brown, and rarely exceeds one half an inch in thickness.
The Swamp White Oak
Q. platanoides, Sudw.
The swamp white oak loves to stand in wet ground, sometimes even in actual swamps. Its small branches shed their bark like the buttonwood, the flakes curling back and showing the bright green under layer. On the trunk the bark is thick, and broken irregularly into broad, flat ridges coated with close, gray-brown scales often tinged with red.
In its youth the swamp white oak is comely and symmetrical, its untidy moulting habit concealed by the abundant foliage. One botanist calls this species bicolor, because the polished yellow-green upper surfaces contrast so pleasantly with the white scurf that lines each leaf throughout the summer. Yellow is the autumn color. Never a hint of red warms this oak of the swamps, even when planted as a street or park tree in well-drained ground.
The Basket Oak
Q. Michauxii, Nutt.
The basket oak is so like the preceding species as to be listed by some botanists as the southern form of Q. platanoides. They meet on a vague line that crosses Maryland, Kentucky, and Tennessee. Both have large leaves silver-lined, with undulating border, of the chestnut oak pattern. Both are trees of the waterside, tall, with round heads of gnarled limbs. The red-tinged white bark sets the basket oak apart from all others. Its head is broader and its trunk stouter than in the other species. The paired acorns are almost without stalks, the nuts large, the kernels sweet. In autumn, farmers turn their hogs into the woods to fatten on this oak-mast. The edibility of these nuts may account for the common name, "cow oak."
The wood splits readily into thin, tough plates of the summer wood. This is because the layer formed in spring is very porous. Bushel baskets, china crates, and similar woven wares are made of these oak splints. The wood is also used in cooperage and implement construction, and it makes excellent firewood.
The live oak with its small oval leaves, without a cleft in the plain margins, looks like anything but an oak to the Northerner who walks along a street planted with this evergreen in Richmond or New Orleans. It is not especially good for street use, though often chosen. It develops a broad, rounded dome, by the lengthening of the irregular limbs in a horizontal direction. The trunk becomes massive and buttressed to support the burden.
The "knees" of this oak were in keenest demand for ship-building before steel took the place of wood. In all lines of construction, this lumber ranks with the best white oak. The short trunk is the disadvantage, from the lumberman's viewpoint. Its beauty, when polished, would make it the wood par excellence for elegant furniture, except that it is difficult to work, and it splits easily.
The Spanish moss that drapes the limbs of live oaks in the South gives them a greenish pallor and an unkempt appearance that seems more interesting than beautiful to many observers. It is only when the sight is familiar, I think, that it is pleasing. Northern trees are so clean-limbed and so regular about shedding their leaves when they fade, that these patient hosts, loaded down with the pendent skeins of the tillandsia, seem to be imposed upon. In fact, the "moss" is not a parasite, sapping the life of the tree, but a lodger, that finds its own food supply with-out help.
California White Oak Q. lobata, Née.
The California white oak far exceeds the Eastern white oak in the spread of its mighty arms. The dome is often two hundred feet in breadth and the trunk reaches ten feet in diameter. Such specimens are often low in pro-portion, the trunk breaking into its grand divisions within twenty feet of the ground. The ultimate spray is made of slender, supple twigs, on which the many-lobed leaves taper to the short stalks. Dark green above, the blades are lined with pale pubescence. The acorns are slender, pointed, and often exceed two inches in length. Their cups are comparatively shallow, and they fall out when ripe.
The bare framework of one of these giant oaks shows a wonderful maze of gnarled branches, whose grotesque angularities are multiplied with added years and complicated by damage and repair.
It is hard to say whether the grace and nobility of the verdure-clad tree, or the tortuous branching system revealed in winter, appeals more strongly to the admiration of the stranger and the pride of the native Californian, who delights in this noble oak at all seasons. Its comparatively worthless wood has spared the trees to adorn the park-like landscapes of the wide middle valleys of the state.
Pacific Post Oak
Q. Garryana, Hook.
The Pacific post oak is the only oak in British Columbia, whence it follows down the valleys of the Coast Range to the Santa Cruz Mountains. It is a tree nearly one hundred feet high, with a broad, compact head, in western Washington and Oregon. Dark green, lustrous leaves, with paler linings, attain almost a leathery texture when full grown. They are four to six inches long and coarsely lobed. In autumn they sometimes turn bright scarlet.
The wood is hard, strong, tough, and close-grained. It is employed in the manufacture of wagons and furniture, and in ship-building and cooperage. It is a superior fuel.
THE BLACK OAK GROUP
A large group of our native oaks require two seasons to mature their acorns; have dark-colored bark and foliage, have leaves whose lobes are sharp-angled and taper to bristly points and tough acorn shells lined with a silky-hairy- coat.
The Black Oak
Q. velutina, Lam.
The black oak of the vast region east of the Rocky Mountains is the type or pattern species. Its leathery, dark green leaves are divided by curving sinuses into squarish lobes, each ending in one or more bristly tips. The lobes are paired, and each has a strong vein from the midrib. Underneath, the leaf is always scurfy, even when the ripening turns its color from bronze to brown, yellow or dull red.
Under the deep-furrowed, brown surface bark is a yellow layer, rich in tannin, and a dyestuff called quercitron. This makes the tree valuable for its bark. The wood is coarse-grained, hard, difficult to work, and chiefly employed as fuel.
A distinguishing trait of the bare tree is the large fuzzy winter bud. The unfolding leaves in spring are bright red above, with a silvery lining.
The autumn acorn crop may be heavy or light. Trees have their "off years," for various reasons. But always, as leaves and fruit fall and bare the twigs, one sees, among the winter buds, the half-grown acorns waiting for their second season of growth.
The pointed nut soon loosens, for the cup though deep has straight sides. The kernel is yellow and bitter.
The Scarlet Oak Q. coccinea, Moench.
The scarlet oak is like a flaming torch set among the dull browns and yellows in our autumnal woods. In spring the opening leaves are red; so are the tasselled catkins and the forked pistils, that turn into the acorns later on. This is a favorite ornamental tree in Europe and our own country. Its points of beauty are not all in its colors.
The tree is slender, delicate in branch, twig, and leaf—quite out of the sturdy, picturesque class in which most oaks belong. The leaf is thin, silky smooth, its lobes separated by sinuses so deep that it is a mere skeleton compared with the black oak's. The trimness of the leaf is matched by the neat acorn, whose scaly cup has none of the looseness seen in the burly black oak. The scales are smooth, tight-fitting, and they curl in at the rim.
There is lightness and grace in a scarlet oak, for its twigs are slim and supple as a willow's, and the leaves flutter on long, flexible stems. Above the drifts of the first snowfall, the brilliance of the scarlet foliage makes a picture long to be remembered against the blue of a clear autumnal sky.
The largest trees of this species grow in the fertile up-lands in the Ohio Valley. But the most brilliant hues are seen in trees of smaller size, that grow in New England woods. In the comparatively dull-hued autumn woods of Iowa and Nebraska the scarlet oak is the most vivid and most admired tree.
The Pin Oak
Q. palustris, Linn.
The pin oak earns its name by the sharp, short, spur-like twigs that cluster on the branches, crowding each other to death and then persisting to give the tree a bristly appearance. The tree in winter bears small resemblance to other oaks. The trunk is slender, the shaft carried up to the top, as straight as a pine's. The branches are very numerous and regular, striking out at right angles from the stem, the lower tier shorter than those directly above them, and drooping often to the ground.
On the winter twigs, among the characteristic "pins," are the half-grown acorns that proclaim the tree an oak beyond a doubt, and a black oak, requiring a second summer for the maturing of its fruit. It is likely that there will be found on older twigs a few of the full-grown acorns, or perhaps only the trim, shallow saucers from which the shiny, striped, brown acorns have fallen. Hunt among the dead leaves and these little acorns will be discovered for, though pretty to look at, they are bitter and squirrels leave them where they fall.
The leaves match the slender twigs in delicacy of pat-tern. Thin, deeply cut, shining, with pale linings, they flutter on slender stems, smaller but often matching the leaves of the scarlet oak in pattern. Sometimes they are more like the red oak in outline. In autumn they turn red and are a glory in the woods.
One trait has made this tree a favorite for shade and ornament. It has a shock of fibrous roots, and for this reason is easily transplanted. It grows rapidly in any moist, rich soil. It keeps its leaves clean and beautiful throughout the season. Washington, D. C., has its streets planted to native trees, one species lining the sides of a single street or avenue for miles. The pin oaks are superb on the thoroughfare that reaches from the Capitol to the Navy Yard. They retain the beauty of their youth be-cause each tree has been given a chance to grow to its best estate. In spring the opening leaves and pistillate flowers are red, giving the silvery green tree-top a warm flush that cheers the passerby. In European countries this oak is a prime favorite for public and private parks.
The Red Oak Q. rubra, Linn.
The red oak grows rapidly, like the pin oak, and is a great favorite in parks overseas, where it takes on the rich autumnal red shades that give it its name at home. Such color is unknown in native woods in England.
The head of this oak is usually narrow and rounded; the branches, short and stout, are inclined to go their own way, giving the tree more of picturesqueness than of symmetry, as age advances. Sometimes the dome is broad and rounded like that of a white oak, and in the woods, where competition is keen, the trunk may reach one hundred and fifty feet in height.
The red oak leaf is large, smooth, rather thin, its oval broken by triangular sinuses and forward-aiming Iobes, that end in bristly points. The blade is broadest between the apex and the middle, where the two largest lobes are. No oak has leaves more variable than this.
Under the dark brown, close-knit bark of a full-grown red oak tree is a reddish layer that shows in the furrows. The twigs and leaf-stems are red. A flush of pink covers the opening leaves, and they are lined with white down which is soon shed.
The bloom is very abundant and conspicuous, the fringe-like pollen-bearing aments four or five inches Iong, drooping from the twigs in clusters, when the leaves are half-grown in May.
The acorns of the red oak are large, and set in shallow saucers, with incurving rims. Few creatures taste their bitter white kernels.
The Willow Oak Q. Phellos, Linn.
The willow oak has long, narrow, pointed leaves that suggest a willow, and not at all an oak. The supple twigs, too, are willow-like, and the tree is a lover of the waterside. But there is the acorn, seated in a shallow, scaly cup, like a pin oak's. There is no denying the tree's family connections.
A southern tree, deservedly popular in cities for shade and ornamental planting, it is nevertheless hardy in Philadelphia and New York; and a good little specimen seems to thrive in Boston, in the Arnold Arboretum. As a lumber tree, the species is unimportant.
The Shingle, or Laurel, Oak
Q. imbricaria, Michx.
The shingle or laurel oak may be met in any woodland from Pennsylvania to Nebraska, and south to Georgia and Arkansas. It may be large or small; a well-grown specimen reaches sixty feet, with a broad, pyramidal, open head.
The chief beauty of the tree, at any season, is the foliage mass—dark, lustrous, pale lined, the margin usually unbroken by any indentations. In autumn the yellow, channelled midribs turn red, and all the blades to purplish crimson, and this color stays a long time. It is a wonderful sight to see the evening sunlight streaming through the loose, open head of a laurel oak. No wonder people plant it for shade and for the beauty it adds to home grounds and public parks.
The Mountain Live Oak
Q. chrysolepis, Liebm.
The mountain live oak cannot be seen without climbing the western slopes of the mountains from Oregon to Lower California, and eastward into New Mexico and Arizona. On levels where avalanches deposit detritus from the higher slopes, sufficient fertility and moisture are found to maintain groves of these oaks, wide-domed, with massive, horizontal branches from short, buttressed trunks—the Western counterpart of the live oak of the South, but lacking the familiar drapery of pale green moss.
The leaves are leathery, polished, oval blades, one or two inches in length, with unbroken margins, abundant on intricately divided, supple twigs, that droop with their bur-den and respond to the lightest breeze. The leaves persist until the bronze-green new foliage expands to replace the old, and keep the tree-tops evergreen.
The acorns are large, and their thick, shallow saucers are covered with yellow fuzz. For this character, the tree is called the gold-cup oak. In June, the copious bloom is yellow. Even at an altitude of eight thousand feet the familiar gold-cup acorns are borne on shrubby oaks not more than a foot high !
The maximum height of the species is sixty feet. The wood is the most valuable oak of the West Coast. It is used for wagons and agricultural implements.
The Live Oak Q. agrifolia, Née.
The live oak (Q. agrifolia, Née.) called also "Enema," is the huge-limbed, holly-leaved live oak of the lowlands, that reaches its greatest abundance and maximum stature in the valleys south of San Francisco Bay. The giant oaks of the University campus at Berkeley stretch out ponderous arms, in wayward fashion, that reach far from the stocky trunk and often rest their mighty elbows on the ground. The pointed acorns, usually exceeding an inch in length, are collected by woodpeckers, and tucked away for further reference in holes they make in the bark of the same oaks.
From the mountain slopes to the sea, and from Mendocino County to Lower California, groves of this semi-prostrate giant are found, furnishing abundant supply of fuel, but no lumber of any consequence, because the trunks are so short and the limbs so crooked.