Probably both authorities are right, and the habits of the trees are even now undergoing a change. It may be that the elms, which are gradually learning to bear stamens and pistils in separate flowers, are also, by slow degrees, dispensing with the services of that wasteful pollen-carrier, the wind, and learning to utilize those safer and surer messengers, flying insects. In some future day they may reach the condition of the red maples, which are almost wholly dependent upon insect ministrations.
All the earliest tree-blossoms, poplar, swamp-willow, elm, and red maple, come out of buds which contain flowers only. On the trees which bear them are other buds from which the foliage expands later. But some buds contain both foliage and flowers. The great horse-chestnut buds, those of the pear-tree, and those of the buckeye, let out into the sun a whole cluster of leaves, surrounding a pyramid or bunch of buds. Mother Nature's spring parcels are coming undone, and we see, with astonishment, how much they have held. Their opening is as surprising as the unpacking of that hat from which the conjurer draws enough articles to fill a Saratoga trunk. The horse-chestnut buds, in latter March, are no bigger than thimbles, yet from them issue in April weather four, or even six, broad, fan-like leaves, surrounding a cone-shaped cluster of flowers (Fig. 7).
Fig. 7. - (a) Sleeping and (b)expanding buds of the horse-chestnut.
(From the Vegetable World).
When the young leaves first begin to expand we can see the folding creases in them, and thus get an idea how they were packed into the very small spaces which they occupied all winter. We see that maple and currant leaves have been plaited like fans. Those of the cherry and oak have been folded lengthwise down the middle, so that their sides come together like the covers of a closed book. The circular May-apple leaves have been folded back against their stalks, like closed umbrellas, and will open just as umbrellas do. Plum-leaves have been rolled from one edge toward the other, as one rolls sheets of music. Some of the tender young leaves are clothed or surrounded with vegetable down. This is the blanketing which Nature provided to prevent them from being "winter-killed." The horse-chestnut leaves have been particularly well protected, and from seeing them so snugly wrapped we infer that this tree's ancestors lived in the north, where winters were long and severe. Its cousin, the buckeye, is a fair southerner, and the young buckeye leaves are unprovided with coverings of vegetable wool, which, in a mild climate, are unnecessary.
May-apple (Podophyllum pellatum)
But we must not infer that every unprotected bud found in northern woods is borne on a vegetable stray from a milder climate. A few northern plants have become so thoroughly case-hardened to winter and rough weather that they have dispensed with protective bud-wrappings. Like some intrepid folk of our acquaintance they get through the cold season without an overcoat, or independent of furs and flannels.
The winter buds of the blackberry are protected only by a few thin scales, often too short to cover the tips of the young leaves within. Four, or at most six, soft scales have defended the elder leaves and the clustered blossom-buds from last winter's frost. The tender foliage of the "wayfaring-tree" or "hobble-bush" has had no protection save a coating of scurf, and with this scant clothing it can survive a Maine winter. But as a rule, when naked buds occur in our climate they are small, and during winter they lie in hiding, sunk into the bark or even partly buried in the wood.
The scales which enclose most native buds are imperfect leaves, detailed to do guard duty. Through the winter they have been wrapped closely around the baby foliage to protect it from rotting damp, and from sudden changes of temperature. Now their work is done, and in a few days they will fall off, or shrivel away, leaving scars upon the twigs to mark the place where they grew. The traces left by fallen bud-scales look as if a string had been wound with the utmost tightness around the branch, so as to encircle it four or five times, and had remained long enough to cut into the bark (Fig. 8). By counting these marks one can tell how many years a branch is old. After a while, by the peeling away of the outermost layers of bark, the scars upon it disappear. In the Willow we can scarcely find them at any stage of the branches' growth, as the budscales are too small to leave well-defined marks. But in maples and horse-chestnuts the marks of the bud-scales of vanished springs are easily-seen. The spaces between them vary from one inch to six or eight, for growth differs in different years, in different trees, or in different branches of the same tree, according to the humidity and heat of the season, the richness of the soil, or the inherent vigor of the individual.
Fig. 8. - Apple twig, showing old bud-scale marks.
At the very heart of each bud which tips a bough or twig is the " apex of growth," a group of generative cells on whose strength and activity the prolongation of the branch depends. The extension of the bough for the season is over and done at a comparatively early period. In many trees it is completed a month after the first little leaves unfold.
By mid-July even the most procrastinating of trees and shrubs have made the growth of the year, and formed next season's buds. Their subsequent efforts are devoted to perfecting and strengthening the young parts, and to laying by a store of nourishment against the needs of another spring.
A leaf-bud is generally formed just above the foot-stalk of a leaf. On a very young branch the twigs spring from the places whence leaves fell in bygone autumns. But some of these twigs will be snapped off by gales, or blighted by insects, and some will be starved and crowded out by more vigorous neighboring twigs. In early spring many leaf-buds of forest-trees are eaten by squirrels, which have waked up hungry after their long winter's nap, and find that the world as yet contains little provender for them. And as every one of these devoured buds is a potential branch, their taking-off will affect the shape of the trees in years to come.
So from various causes the trees of the wood do not show that symmetry in the positions of their boughs which we admire in the arrangement of their leaves. Indeed, the branching of a full-grown tree bears little relation to the positions of the buds from which those branches sprang.
The symmetry of the adult shrub or tree is further marred by the occasional development of what are called "supernumerary" or" accessory' buds. These are found especially on low-growing plants, likely to be browsed upon by cattle.
When a leaf drops off the bramble, for instance, it leaves a group of buds, a larger one in the centre with one, or, it may be, two smaller ones on either side.
These are understudies, as it were, to the middle bud, ready to take up its work in the world if it be killed or disabled. Normally it grows and they remain quiescent. But it may be that one of the side buds is the strongest of the group and lives down all its fellows. It is a question of survival of the fittest.
The common locust has several "accessory buds" under the leaf-stalk, and a principal bud in the scar left by the leaf of last summer. This axillary bud may be overtaken in growth by the strongest one in the group below it, so that in years to come the tree will have two branches almost together.
In the poplar, elm, and willow extra buds are potentially present in the bark, and will develop in numbers if the tree is maimed. Such buds and growths are called "adventitious," and have no relation whatever to the ordinary position of the leaves. Those of the elm sometimes appear on the trunk in dense tufts of whip-like branches.
The basket-makers turn the willow's ability to produce adventitious buds to excellent account. They cut off the crown of the tree, and the ends of its principal branches, and there results an outgrowth of the tough, lithe osiers from which baskets and chair-seats are woven.
The willow is about the first of our native trees to put forth foliage. The elm, ash, and oak - canny northerners all - are late, and their leafing has given rise to some quaint rural sayings. The peasantry of the old world have been accustomed from time immemorial to arrange their farming pursuits according to indications given by certain trees and flowers. "The leafing of the elm," says Thistleton Dyer, "has for generations been made to regulate agricultural doings, and hence the old rule:
'When the elmen-leaf is as big as a mouse's ear, Then to sow barley never fear.' "
With which may be compared another piece of weather-lore:
"Whenthe oak puts on his gosling gray, Tis time to sow barley night or day".
The oak and the ash come into leaf almost together, and rural folk used to watch the trees to find out whether the coming summer would be a rainy or a dry one.
"If the oak is out before the ash, 'Twill be a summer of wet and splash;
If the ash is before the oak,
'Twill be a summer of fire and smoke," says an old piece of weather-lore.
Nourishing gums and starches are stored away all winter in the tree-trunks and branches, and toward spring they feel their way along the least twigs and into the buds where life has begun to stir.
The store of nourishment which sustains this year's expanding foliage was collected last summer by the leaves which have now rotted away under the winter rains, or drifted into sheltered hollows, where they lie, withered and sere.
When this year's leaves have attained full strength and maturity, they in their turn will gather food which is to be put by, not for themselves, but for those which come after them. So some labor and others enter into the fruits of their labor, not only among humanity, but even in the vegetable world. And so the great lesson of Easter-tide, the lesson of self-sacrifice, is suggested by the story of the awakening April woods.