Part 17

One of the first tree families whose name we learn is the willow family. The members are numerous, and the botanists find great difficulty in distinguishing certain species, which closely resemble each other; but these troubles we shall leave to the scientist. The point for us to consider is this: When we see a tree which we know to be a willow, how do we know it? “It looks like a willow,” some one says. But who knows, and can tell how willows look—how they differ from other trees?

First, willows have slender, flexible twigs that give the tree tops grace and lightness. Second, willow leaves are nearly always long and slim to match the supple twigs. They are always simple, and short-stemmed. The wood is light and soft, so the trees break easily in storms of wind and ice. An old willow tree is likely to be crippled, but its scars and wounds are covered in summer by the arching branches and the abundant foliage.

The first trees to blossom in spring are the shrubby pussy willows, a distinct kind whose catkins are so eager to push out of their scales that their grey, silky noses are often seen in November. Frequently, they are out and the scales dropped in February; but the yellow stamens and the long-tongued pistils do not rise above the grey fur until March, at least. The most attractive stage of these catkins is the earlier one, when the flower buds are concealed by the grey silk.

By cutting pussy willow twigs in the late fall, or any time during the winter, and putting them into a jar of water, we may see the blossoming, quite out of season. Sufficient food is stored in the twig to force out the blossoms, even to the shedding of the pollen. It is a charming thing in the winter to have a vase of these twigs in full bloom on a window sill when snow banks are piled high just outside.

Willows are lovers of wet ground, and we shall see groves of them scattered along streams and on the margins of ponds and swamps. A few species thrive in dry soil, and seem to prefer it. Some grow at sea level, others are found on high mountains. From small shrubs they vary to mighty trees. There is no climate and no soil that does not have its native willows. The family is distributed from the Equator to the Arctic Circle.

It is very common in many places for farmers to plant a grove of willows for a windbreak, to protect their houses and barns. This is especially seen in prairie states and other treeless regions. Willows are quick-growing trees, and sure to grow. All one needs do is to cut limbs from a growing tree, chop these limbs into pieces the length of stove wood, and drive them into the ground. Each one takes root, and grows into a tree, if the soil is at all moist.

Another plan is to cut fence posts from the willow grove, and drive them into the ground. Each of these posts forms the trunk of a willow tree, which soon has a great head of branches.

In Holland and other countries, willows are thickly planted to form hedges and for their roots to hold the soil along the banks of streams and ditches. The same trees may perform a double service. Willow wood makes good summer fuel, where a quick, hot fire is desired. The twigs make the best charcoal used in the manufacture of gunpowder. The long, flexible twigs of a low-growing willow are used in the manufacture of wicker chairs, tables, and other furniture. These trees are grown on a large scale in France and other European countries, and the industry is being introduced in some parts of America.

When spring comes on, we may notice a peculiar change in the colour of the bare willows that line the stream borders. The twigs turn gradually green, and the long, pointed buds prepare to cast off their single scales. These are shaped like the long, knitted caps which children wear in winter time, although there is no tassel at the end. The cap fits snugly over the long bud, and is fastened in a circle at the joint. The swelling bud simply pushes it off.

Under these trees, we shall find a good many fresh twigs. Reaching up to break one, we find that it snaps off short at the base. It is not brittle along its whole length. Try a dozen twigs, and off they snap, almost at a touch. The wind has broken off those that fell to the ground. Some that fall in the water, float away down stream. They catch on sandbars, and strike root. Some swing in to the shore, and grow on the banks.

We have discovered a habit of certain kinds of willow trees. The shedding of their twigs at the season when they are fullest of life is the tree’s method of colonising new territory. These twigs float away, and blow away, and those which lodge in wet ground before they dry are almost sure to grow. The billowy acres of green which cover sandbars and stream borders are willow trees, children of parents that grow far up stream.

Along roadsides in this country a large willow is much planted, whose leaves are pale beneath, so that they look very cheerful and cool in midsummer. The most striking thing about these willows is that their twigs are yellow as ducks’ feet, and particularly bright in early spring. The older trees grow very stout, and great branches leave the trunk close to the ground. This is the golden osier willow, one form of the white willow of Europe, which does not grow vigorously in this country.

The weeping willows, whose long, supple branches sweep out and downward, sometimes yards in length, from the tree top, came originally from Babylon. Who were they in that far country who “hung their harps on the willow trees”? A great many weeping willows in the Eastern states are said to be sprung from the parent tree, which grew on the Island of St. Helena. What famous prisoner probably sat under the shadows of this willow tree, and dreamed again of conquering the world? The weeping willow has the habit of snapping its twigs off, short, at the base. One of these long withes, cut into bits with one or two buds on each cutting, will start as many weeping willow trees, if the bits are stuck into wet sand and kept wet until rooted, and then set out and given plenty of water until they become established in the ground.

The black willow is named for the black bark of the old tree. It is the only one of the narrow-leaved willows whose leaves are uniformly green on both sides. These leaves are often curved like a sickle. At the base of each leaf is a pair of heart-shaped, leafy blades, called stipules. Many trees have stipules that come out with the leaves, and are dropped off, but these persist, as a rule, all summer. The black willow is one of those with the twigs that snap. It takes possession of stream borders, and its offspring may cover miles of new territory in a single season.

The balsam willow we shall know by the fragrant coating of wax, or balsam, on its young shoots and buds. Its broad leaves are blunt at the tip, and look scarcely willow-like, but the tree is known by its buds and its catkins. To find it we shall have to go into the boggy regions in the Northern tier of states, where it is numerous, but never more than a shrubby tree.

One use is served by no tree as well as a willow. When the sap rises in spring, the willow branches are in prime condition to make whistles. I wonder if there is a boy, in town or country, who does not know how to make a willow whistle that will “go”? Surely not, unless his supply of uncles and grandfathers is short. You cannot make a willow whistle by following printed directions. Some skilful person, who has been a boy, must show you, and one lesson is enough.

WHY TREES NEED LEAVES

Spring or early summer is the best time to study the leaves of trees. They are clean, and fresh, and new. Every tree is a great mound of green. The broad-leaved trees seem to be thatched or shingled with overlapping blades so that no sunlight can get into the darkened room, which is empty except for the bare branches that support this outer dome of leaves. A sugar maple, or a linden tree, shows best this outer thatch, which is so thick that the sun is unable to look through. The bird flying overhead sees only a solid mass of leaves. The one on its nest in a forked limb looks up and sees the inside of this leafy tree cover. She is glad for the twilight that surrounds her, and for the coolness of this shady place; but more glad that her nest is hidden from sight of hawks that sail overhead, while she keeps a close watch for sly, thieving red squirrels that may come to steal her eggs, by climbing up the branches.

What are the leaves for? Why does the tree put out in spring young shoots with rows of leaves along their sides? Why does the tree hold these branches out as far as possible from the trunk, and bend the leaf stems and the twigs so as to face the leaf blades towards the sun?

The reason is this: the life of the trees is in the green layer which we see on the surface of all green shoots, and which we can discover under the older bark of twigs, which has turned brown. Following the twig back from its tip, all of the leafy part is green. Behind it the smooth twig is no longer green, but a thumb nail easily strips off the layer of brown, and reveals the green under bark. Go a little further back, and gradually the outer bark thickens, and it is more difficult to get at the soft under layer. After a while, we shall need a knife to reach it, for old bark is hard and tough.

When the bark gets so thick that the sun cannot reach the green layer, the colour fades out. The living part of the trunk of the tree is the soft, juicy layer between the bark and wood. Through this portion of the tree the sap rises from the roots, and finally reaches the leaves. This sap needs to be changed before it can be useful to the tree as food.

The leaves are the places where these changes take place. Through little doorways in the under sides of the leaf air passes in. With it goes carbonic acid gas, an important food element. The soft green leaf pulp, which is the green juice of a bruised leaf, has a wonderful work to do. It cannot do this work unless the sun is shining upon it. On a bright day every leaf is making starch, and sending it down through the twigs and branches as food. This starch is contained in the sugary sap that flows back constantly from the leaves to the farthest root tips. It is made in the leaves out of the sap brought up from the roots and the carbonic acid gas which the leaves absorb from the air.

As long as the leaves do their work, the tree is able to grow, and to blossom, and to ripen its seeds. When the leaves have done their work the summer has passed; the tree lets go the leaves, and rests without growing all winter.

It is not easy to explain the work of the leaves, nor even to understand the wonderful work accomplished there all through the summer. When we eat, our food must go into the stomach to be changed by the processes called digestion. It is hours before the digested food is poured into the blood and carried to all parts of the body. The tree takes its food from the air, and from the soil. Neither the dirty water that rises as sap to the leaves, nor the gas which enters the leaf doorways from the air, is useful as food to the growing tree until they have been combined and changed. The leaves are, then, in a sense, the stomachs of the trees, for in them the raw foods must be “digested” before they are ready to be poured into the life blood that flows down through all the live parts of the tree. Now they are fit to feed the growing cells, which are always hungry.

LEAVES OF ALL SHAPES AND SIZES

The leaf of the tree is its visiting card. We shall learn to know trees by their leaves, as easily as if the name were written across the face of the leaf. Some leaves have a single blade of green, and for this reason the botanist calls them simple leaves. This blade has a stem that unites it with the twig. A compound leaf is one whose stem bears more than one blade. These small blades are called leaflets. There are two types of compound leaves, one feather-like, having a main stem with leaflets arranged in two rows on opposite sides of this stem. Such a leaf is feather-like. The other type has a leaf stem with all the leaflets attached at one end. The horse chestnut is the best example of this type. The leaves spread from the end of the stalk somewhat as the fingers rise from the palm of your hand.

The biggest leaves with single blades to be found in our forests grow on trees of the magnolia family. The silver-lined leaves of the large-leaved cucumber tree are over a foot in length, sometimes two and one-half feet, down South. These great leaves are about one-fourth as wide as long, and at the base each one broadens and extends backward into two rounded ear-like lobes. This gives the tree the name, ear-leaved magnolia. The whole leaf flaps in the wind, like the ear of an elephant, and, of course, the wind lashes it into strings and soon robs it of its beauty.

The Northern cucumber tree is another magnolia whose leaves are tropical-looking. This is the hardiest of the magnolia family, and its heart-shaped leaves are six to ten inches long. They are not large for a magnolia of the South, but they look larger because they grow among the small-leaved trees of the Northern states.