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Tree seeds


when we want a symbol of independance we are wont to point to a great tree - a sturdy oak, perhaps. Yet how helpless trees are, after all! Like Prometheus chained to the rock, they cannot move, while creatures smaller than eagles but fully as ravenous, come to prey upon them. Their sacred mission in life is the propagation of their kind. Yet in performing it how dependent are they upon blind chance!

There are great epochs in the lives of trees, and great days in each year's calendar. Critical indeed is the time when the flowers open and the pollen is given to the wind and to the insects. Upon these unconscious and irresponsible agents largely depends the setting of seed. The maturing of the seed may soon be accomplished, or it may be a long, slow process, which fills a whole summer, or even two. With its completion another critical epoch is at hand. The tree yields its precious seeds to the heedless wind or drops them upon the ground. The fate of each tree-child trembles in the balance while the parent tree is powerless to take any further part in the great work of seed distribution.

As a matter of fact this point of view is altogether human and somewhat sentimental. There is not so much chance, after all. The bee is wonderfully efficient in the pollination of flowers. She attends strictly to business, and for her the day is long. Between dawn and dusk she, visits countless flowers. The wind may be a reckless fellow, but he often works while we sleep or play. Then, too, many species of trees will survive without cross-fertilization or wide dissemination. Trees have ways of propagating their kind that do not involve the seed at all. But, what subject is so interesting as the flight of seeds? No wonder it appeals to the imagination and holds the attention of us all!

The seed of ash trees is like a dart. A flat pointed case contains the embryo, and out behind it extends a thin, light two-edged wing. The seeds hang in clusters securely fastened on wiry stems. They break loose a few at a time in high winds, and flutter and hesitate as they turn over, to point their heavy ends downward. They may go like all arrow straight into the snow or the leaf mould under the tree; or, if the wind is blowing a gale, the seed may be caught by the current and borne far away before a lull lets the little dart point downward again and the seed find its way to the earth.

The willow is one of the earliest trees to ripen its seeds. The long terminal catkin hangs for days with little green pods along its sides. Then suddenly the pods burst, the two halves curl back out of the way, and the tiniest specks of seeds float out. Each one is hid in a misty tuft of silk which is so light it seems as if it would never reach the earth, and in truth, much of it never does. Whether it does or not makes little difference to the willows. So feeble is the embryo in the seed that it dies in a day if it is not lodged in a place favorable for its germination. Willows do not depend upon their seeds. Blossoming and seed-growing is with them largely a matter of form - of loyalty to the traditions of their family.
Multiplication is much more surely and vigorously accomplished by casting off twigs and branches which strike root in moist soil near the tree, or float down stream, lodging and growing on sand-bars or river banks. Thus do willows spread, while the wind is busy scattering their ineffectual seeds.

In April the elm trees, leafless yet, show the green tips of opening leaf buds, but much more noticeable are the green seeds that hang like dainty pendants in clusters from the sides of twigs. Because they are many, the ground is thickly sprinkled with seeds which the tree call not ripen. By the time the leaves are full-sized the seeds are ripe and scattered. Each is a thin flat disk with the embryo in the center of a surrounding wing.

The American elm has a fringed seed, with two incurving hooks that meet at the apex. These seeds float far on the wind, for they are as light as feathers. All winter the button balls dangle by their stringy steins on the twigs of the buttonwood trees. They bang against each other and against the neighboring limbs when the wind whips them to and fro. The seeds are dry and ripe. They stand as thick on a central pit as grains of corn on the cob.

At length a bump harder than usual loosens the attachment of a few of these seeds. They bulge out, and the next bump sets them free. In a short time not a seed is left on that particular button. Each little seed is shaped like a slender cone, attached by its pointed end. Near the tip is a whorl of yellow hairs which spreads and forms a parachute that checks the seed's headlong flight to the ground and bears it some distance.

The catalpa tree stands all winter hung with its pencil-like pods. The two valves loosen gradually as the winds buffet them, and the seeds slip out, one by one. And a strange looking seed it is! From the central embryo, two long wings, thin as tissue paper, taper into ragged fringes. The whole thing looks like a wraith of a seed, from which nothing might be expected. The hop hornbeam or ironwood sends its seeds, afloat in balloons. Take off one of these little paper bags, open it, and you will find set at its base a shiny, pointed seed. There is likely to be a long journey before this seed, for until it is safely underground, or its bag punctured, the wind gives it no rest.

The hornbeam has a quaint little scallop shell on which. its seed is launched. The seed itself is firmly fastened in the prow of the boat and the wind carries it, careering in many directions before it finds its last resting place. The slim blade in which the ailanthus embryo sets sail is like a long, tilting raft. In winter the clusters of seeds seem fairly to burden the tree. One by one the little rafts let go their hold and sail away. Did you ever lie under a silver maple tree in June and watch the falling seeds? They are twins as they grow on the tree, but they separate when ripe and each takes flight alone. The heavy tip goes first, and the wing whirls madly round and round as the descent is made. The maples are many, but they all bear winged, lop-sided seeds which whirl and flutter away before the wind, or fall to the ground under the tree when there is no breeze to carry them farther.

All the conifers open the scales of their ripened cones and give to the winds a delicate winged seed which looks like a miniature maple key. Some cones stand erect and, curling back their loosening scales, fairly unseat the seeds and shove them forth. The cones of other trees hang down and the seeds fall out as the scales relax and spread and dry.

On the basswood trees the seed clusters cling long after the leaves have fallen. They are downy little balls, each with one or two good seeds in it, and all are joined on a single stem which grows out of the middle of a leaf-like blade. When this stem lets go its hold upon the tree the broad blade acts as a parachute. The wind takes a keen interest in it. Gravitation and buoyancy have a strife for mastery, and the basswood seeds generally fall to earth some distance from the tree that bore them.

The honey locust has long purplish hods, which rattle their hard little seeds as they fall in winter. The wind catches the curving blades and tilts them out, of equilibrium. Always a resisting face is presented, always the breeze resents it, and the pod knows no rest until it is anchored by some weight which defeats the lifting power of the wind. So honey locust seeds germinate far from the parent tree, while the heavy straight pod of the Kentucky coffee tree lies undisturbed where it fell.

The little Judas tree and the common locust hold out their thin, leathery pods, and as the wind bears thern away the valves part and the seeds are scattered. Birds carry the seeds of many trees and drop them in places remote from the tree that bore them. Many a wilding apple or pear by the roadside grew from seed so distributed. Squirrels gather acorns and other nuts where they fall, and hide them by tens and dozens in little pockets under the snow or leaf mould along their winter runways. They store them for food, but many nuts are left untouched, and spring up into trees. On hillsides acorns may roll some distance. Gusts of wind may snatch them from the twigs and fling them in any direction. As a rule, however, the wind has little to do with the distribution of the heavy seeds of nut-bearing trees.

When we look off over a forest set with broad-leaved trees and conifers, where gleam the white limbs of sycamores, the tattered trunks of birches, against a background of hemlocks and junipers; when we walk through such a wood, breaking off a twig of sweet birch here, and of sassafras there, and picking up chestnuts and hickory nuts under foot, we wonder how the trees all happened thus to mingle together. By what chance does a rock maple grow here and a willow yonder, and a Judas tree between the two? We must watch for the seeds to ripen on these trees, and we must come again to watch the launching of the seeds. Then some of our questions will be answered. Happily, most trees are loath to give up their fruits. Any day in
winter as you walk through the woods you may watch these misers grudgingly dole out their treasures to the insistent wind.