They shall spring up among the grass, as willows by the water courses.
"When I cross opposite the end of Willow Row the sun comes out and the trees are very handsome, like a rosette, pale, tawny or fawn color at base and red-yellow or orange-yellow for the upper three or four feet. This is, methinks, the brightest object in the landscape these days. Nothing so betrays the spring sun. I am aware that the sun has come out of the cloud just by seeing it light up the osiers."
HE willow, Thoreau noted, is the golden osier, a colonial dame, a descendent from the white willow of Europe. It is the most common tree planted along streams to confine them to their channels, and affords an excellent subject for a nature-study lesson. The golden osier has a short though magnificent trunk, giving off tremendous branches, which in turn branch and uphold a mass of golden terminal shoots. But there are many willows besides this, and the one who tries to determine all the species and hybrids must conclude that of making willows there is no end. The species beloved by children is the pussy willow, which is often a shrub, rarely reaching twenty feet in height. It loves moist localities, and on its branches in early spring are developed the silky, furry pussies. These are favorite objects for a nature-study lesson, and yet how little have the teachers or pupils known about these flowers!
Enlarged willow blossoms.
Pistillate blossom showing nectar, gland (left);
Staminate flower showing the nectar, gland (right).
The willow pussies are the pollen-bearing flowers; they are covered in winter by a brown, varnished, double, tentlike bract. The pussy in full bloom shows beneath each fur-bordered scale two stamens with long filaments and plump anthers; but there are no pistils in this blossom. The flowers which produce seed are borne on another tree entirely and in similar greenish gray catkins, but not so soft and furry. In the pistillate catkin each fringed scale has at its base a pistil which thrusts out a Y-shaped stigma. The question of how the pollen from one gets to the pistils of another is a story which the bees can best tell. The willow flowers give the bees almost their earliest spring feast and, when they are in blossom, the happy hum of the bees working in them can be heard for some distance from the trees. The pollen gives them bee bread for their early brood, and they get their honey supply from the nectar which is produced in little jug-shaped glands, at the base of each pollen-bearing flower on the "pussy" catkin, and in a long pocket at the base of each flower on the pistillate catkin. So they pass back and forth, carrying their pollen loads to fertilize the stigmas on trees where there is no pollen. It has been asserted that the pussies, or pollen-bearing flowers, yield no nectar but give only pollen, so that the bee is obliged to seek both trees in order to secure a diet of "balanced ration;" but the person who made this statement had never taken the pains to look at the tiny jugs over-flowing with nectar found at their bases.
The willow pussies.
The staminate blossoms of the willow.
Photo by Verne Morton.
In June the willow seed is ripe. The catkin then is made up of tiny pods, which open like milkweed pods and are filled with seed equipped with balloons. When these fuzzy seeds are being set free people say that the willows "shed cotton."
Although the seed of the willow is produced in abundance, it is hardly needed for preserving the species. Twigs which we place in water to develop flowers will also put forth roots; even if the twigs are placed in water wrong side up, rootlets will form. A twig lying flat on moist soil will push out rootlets along its entire length as though it were a root; and shoots will grow from the buds on its upper side. This habit of the willows and the fact that the roots are long, strong and fibrous make these trees of great use as soil binders. There is nothing better than a thick hedge of willows to hold streams to their proper channels during floods; the roots reach out in all directions, interlacing themselves in great masses, and thus hold the soil of the banks in place. The twigs of several of the species, notably the crack and sand-bar willows, are broken off easily by the wind and carried off down stream, and where they lodge, they take root; thus, many streams are bordered by self-planted willow hedges.
The willow foliage is fine and makes a beautiful, soft mass with delicate shadows. The leaf is long, narrow, pointed and slender, with finely toothed edges and short petiole; the exact shape of the leaf, of course, depends upon the species, but all of them are much lighter in color below than above. The willows are, as a whole, water lovers and quick growers.
Although willow wood is soft and exceedingly light, it is very tough when seasoned and is used for many things. The wooden shoes of the European peasant, artificial limbs, willowware, and charcoal of the finest grain used in the manufacture of gunpowder, are all made from the willow wood. The toughness and flexibility of the willow twigs have given rise to many industries; baskets, hampers, carriage bodies and furniture are made of them. To get these twigs the willow trees are pollarded, or cut back every year between the fall of the leaves and the flow of the sap in the spring. This pruning results in many twigs. The use of willow twigs in basketry is ancient. The Britons fought the Roman soldiers from behind shields of basket work; and the wattled huts in which they lived were woven of willow saplings smeared with clay. Salicylic acid, used widely in medicine, is made from willow bark, which produces also tannin and some unfading dyes.
The pistillate blossoms of the willow.
Photo by Verne Morton.
There are many insect inhabitants of the willow, but perhaps the most interesting is the little chap which makes a conelike object on the twig of certain species of willow growing along our streams. This cone is naturally considered a fruit by the ignorant, but we know that the willow seeds are grown in catkins instead of cones. This willow cone is made by a small gnat which lays its egg in the tip of the twig; as soon as the little grub hatches, it begins to gnaw the twig, and this irritation for some reason stops the growth. The leaves instead of developing along the stem are dwarfed and overlap each other. Just in the center of the cone at the tip of the twig the little larva lives its whole life surrounded by food and protected from enemies; it remains in the cone all winter, in the spring changes to a pupa, and after a time comes forth—a very delicate little fly. The larva in this gall is very hospitable. It has its own little apartment at the center but does not object to having a tenant in its outer chambers, a fact which is taken advantage of by another gall-gnat which breeds there in large numbers. It is well to gather these cones in winter; examine one by cutting it open to find the larva, and place others in a fruit jar with a cover so as to see the little flies when they shall issue in the spring. (See p. 362). For supplementary reading see "Outdoor Studies," page 24.
There is another interesting winter tenant of willow leaves, but it is rather difficult to find. On the lower branches may be discovered, during winter and spring, leaves rolled lengthwise and fastened, making elongated cups. Each little cup is very full of a caterpillar which just fits it, the caterpillar's head forming the plug of the opening. This is the partially grown larva of the viceroy butterfly. It eats off the tip of the leaf each side of the midrib for about half its length, fastens the petiole fast to the twig with silk, then rolls the base of the leaf into a cup, lines it with silk and backs into it, there to remain until fresh leaves on the willow in spring afford it new food.
Photo by W. C. Baker.
Leading thought—The willows have their pollen-bearing flowers and their seed-bearing flowers on separate trees; the bees carry the pollen from one to the other. The willow pussies are the pollen-bearing flowers.
Method—As early in March as is practicable, have the pupils gather twigs of as many different kinds of willows as can be found; these should be put in jars of water and placed in a warm, sunny window. The catkins will soon begin to push out from the bud-scales, and the whole process of flowering may be watched.
1. How can you tell the common willow tree from afar? In what localities do these trees grow? What is the general shape of the big willow? How high is the trunk, or bole? What sort of bark has it? Are the main branches large or small? Do they stand out at a wide angle or lift up sharply? What color are the terminal shoots, or spray?
2. Are the buds opposite or alternate on the twigs? Is there a bud at exactly the end of any twig? How many bracts are there covering the bud?
3. Which appear first, the leaves or the blossoms? Study the pussies on your twigs and see if they are all alike. Is one kind more soft and furry than the other? Are they of different colors?
4. Take one of the furry pussies. Describe the little bract, which is like a protecting hood at its base. What color is the fur? After a few days, what color is the pussy? Why does it change from silver color to yellow? Pick one of the catkins apart and see how the fur protects the stamens.
5. Take one of the pussies which is not so furry. Can you see the little pistils with the Y-shaped stigmas set in it? Is each little pistil set at the base of a little scale with fringed edges?
6. Since the pollen-bearing catkins are on one tree and the seed-bearing catkins are on the other, and since the seeds cannot be developed without the pollen, how is the pollen carried to the pistils? For this answer, visit the willows when the pussies are all in bloom and listen. Tell what you hear. What insects do you see working on the willow blossoms? What are they after?
7. What sort of seed has the willow? How is it scattered? Do you think the wind or water has most to do with planting willow seed?
Seeds of willow.
Photo by Verne Morton.
Work for May or September—
8. Describe willow foliage and leaves. How can you tell willow foliage at a distance?
9. What sort of roots has the willow? Why are the willows planted along the banks of streams? If you wished to plant some willow trees how would you do it? Would you plant seeds or twigs?
10. For what purposes is willow wood used? How are the twigs used? Why are they specially fitted for this use? What is pollarding a tree? What medicine do we get from willow bark?
11. Do you find willow cones on your willows? Cut one of these cones through and see if you can find any seeds. What is in the middle of it? What do you think made the scales of the cone? Do you think this little insect remains in here all winter?
12. In winter, hunt the lower branches of willows for leaves rolled lengthwise making a winter cradle for the young caterpillars of the viceroy.
Supplementary reading—Trees in Prose and Poetry, p. 137.