"By the rivers of Babylon, there we sat down, yea, we wept, when we remembered Zion. Upon the willows in the midst thereof we hanged our harps." Thus sang the Psalmist of the sorrows of the exiles in Babylon, and his song has fastened the name of the great and wicked city upon one of the most familiar willows, while also making it "weep"; for the common weeping willow is botanically named Salix Babylonica.

It may be that the forlorn Jews did hang their harps upon the tree we know as the weeping willow, that species being credited to Asia as a place of origin; but it is open to doubt, for the very obvious reason that the weeping willow is distinctly unadapted to use as a harp-rack, and one is at a loss to know just how the instruments in question would have been hung thereon. It is probable that the willows along the rivers of Babylon were of other species, and that the connection of the city of the captivity and the tears of the exiles with the long, drooping branches of the noble tree which has thus been sorrowfully named was a purely sentimental one. Indeed, the weeping willow is also called Napoleon's willow, because the great Corsican found much pleasure in a superb willow of the same species which stood on the lonely prison isle of St. Helena, and from twigs of which many trees in the United States have been grown.

The willow family presents great contrasts, both physical and sentimental. It is a symbol both of grief and of grace. The former characterization is undoubtedly because of the allusion of the one hundred and thirty-seventh Psalm, as quoted above, thoughtlessly extended through the centuries; and the latter, as when a beautiful and slender woman is said to be of "willowy" form, obviously because of the real grace of the long, swinging wands of the same tree. I might hint that a better reason for making the willow symbolize grief is because charcoal made from its twigs and branches is an important and almost essential ingredient of gunpowder, through which a sufficiency of grief has undoubtedly entered the world!

Willow twigs seem the very essence of fragility, as they break from the parent tree at a touch; and yet one of the willows furnishes the tough, pliable and enduring withes from which are woven the baskets of the world. The willows, usually thin in branch, sparse of somewhat pale foliage, of so-called mournful mien, are yet bursting with vigor and life; indeed, the spread and the value of the family is by reason of this tenacity and virility, which makes a broken twig, floating on the surface of a turbid stream, take root and grow on a sandy bank where nothing else can maintain itself, wresting existence and drawing strength and beauty from the very element whose ravages of flood and current it bravely withstands.

Apparently ephemeral in wood, growing quickly and perishing as quickly, the willows nevertheless supply us with an important preservative element, extracted from their bitter juices. Salicylic acid, made from willow bark, prevents change and arrests decay, and it is an important medical agent as well.

Flexible and seemingly delicate as the little tree is when but just established, there is small promise of the rugged and sturdy trunk that in a few years may stand where the chance twig lodged. And the color of the willows—ah! there's a point for full enthusiasm, for this family of grief furnishes a cheerful note for every month in the year, and runs the whole scale of greens, grays, yellows and browns, and even adds to the winter landscape touches of blazing orange and bright red across the snow. Before ever one has thought seriously of the coming of spring, the long branchlets of the weeping willow have quickened into a hint of lovely yellowish green, and those same branchlets will be holding their green leaves against a wintry blast when most other trees have given up their foliage under the frost's urgency. Often have the orange-yellow twigs of the golden osier illumined a somber countryside for me as I looked from the car window; and close by may be seen other willow bushes of brown, green, gray, and even purple, to add to the color compensation of the season. Then may come into the view, as one flies past, a great old weeping willow rattling its bare twigs in the wind; and, if a stream is passed, there are sure to be seen on its banks the sturdy trunks of the white and the black willows at least. Think of an average landscape with the willows eliminated, and there will appear a great vacancy not readily filled by another tree.

The weeping willow has always made a strong appeal to me, but never one of simple grief or sorrow. Its expression is rather of great dignity, and I remember watching in somewhat of awe one which grew near my childhood's home, as its branches writhed and twisted in a violent rain-storm, seeming then fairly to agonize, so tossed and buffeted were they by the wind. But soon the storm ceased, the sun shone on the rounded head of the willow, turning the raindrops to quickly vanishing diamonds, and the great tree breathed only a gentle and benignant peace. When, in later years, I came to know the moss-hung live-oak of the Southland, the weeping willow assumed to me a new dignity and value in the northern landscape, and I have strongly resented the attitude of a noted writer on "Art Out of Doors" who says of it: "I never once have seen it where it did not hurt the effect of its surroundings, or at least, if it stood apart from other trees, where some tree of another species would not have looked far better." One of the great merits of the tree, its difference of habit, its variation from the ordinary, is thus urged against it.

I have spoken of the basket willow, which is scientifically Salix viminalis, and an introduction from Europe, as indeed are many of the family. In my father's nursery grew a great patch of basket willows, annually cut to the ground to make a profusion of "sprouts," from which were cut the "tying willows" used to bind firmly together for shipment bundles of young trees. It was an achievement to be able to take a six-foot withe, and, deftly twisting the tip of it under the heel to a mass of flexible fiber, tie this twisted portion into a substantial loop; and to have this novel wooden rope then endure the utmost pull of a vigorous man, as he braced his feet against the bundle of trees in binding the withe upon it, gave an impression of anything but weakness on the part of the willow.

Who has not admired the soft gray silky buds of the "pussy" willow, swelling with the spring's impulse, and ripening quickly into a "catkin" loaded with golden pollen? Nowadays the shoots of this willow are "forced" into bud by the florists, and sold in the cities in great quantities; but really to see it one must find the low tree or bush by a stream in the woods, or along the roadside, with a chance to note its fullness of blossom. It is finest just when the hepaticas are at their bluest on the warm hillsides; and, one sunny afternoon of a spring journey along the north branch of the Susquehanna river, I did not know which of the two conspicuous ornaments of the deeply wooded bank made me most anxious to jump from the too swiftly moving train.

This pussy-willow has pleasing leaves, and is a truly ornamental shrub or small tree which will flourish quite well in a dry back yard, as I have reason to know. One bright day in February I found a pussy-willow tree, with its deep purple buds showing not a hint of the life within. The few twigs brought home quickly expanded when placed in water, and gave us their forecast of the spring. One twig was, out of curiosity, left in the water after the catkins had faded, merely to see what would happen. It bravely sent forth leaves, while at the base little white rootlets appeared. Its vigor appealing to us, it was planted in an arid spot in our back yard, and it is now, after a year and a half, a handsome, slender young tree that will give us a whole family of silken pussy-buds to stroke and admire another spring.

This same little tree is called also the glaucous willow, and it is botanically Salix discolor. It is more distinct than some others of the family, for the willow is a great mixer. The tree expert who will unerringly distinguish between the red oak and the scarlet oak by the precise angle of the spinose margins of the leaves (how I admire an accuracy I do not possess!) will balk at which is crack willow, or white willow, or yellow or blue willow. The abundant vigor and vitality and freedom of the family, and the fact that it is of what is known as the di[oe]cious habit—that is, the flowers are not complete, fertile and infertile flowers being borne on separate trees—make it most ready to hybridize. The pollen of the black willow may fertilize the flower of the white willow, with a result that certainly tends to grayness on the worrying head of the botanist who, in after years, is trying to locate the result of the cross!

There is much variety in the willow flowers—and I wonder how many observers really notice any other willow "blossoms" than those of the showy pussy? A superb spring day afield took me along a fascinatingly crooked stream, the Conodoguinet, whose banks furnish a congenial and as yet protected (because concealed from the flower-hunting vandal) home for wild flowers innumerable and most beautiful, as well as trees that have ripened into maturity. An earlier visit at the time the bluebells were ringing out their silent message on the hillside, in exquisite beauty, with the lavender phlox fairly carpeting the woods, gave a glimpse of some promising willows on the other side of the stream. Twilight and letters to sign—how hateful the desk and its work seem in these days of springing life outside!—made a closer inspection impossible then, but a golden Saturday afternoon found three of us, of like ideals, hastening to this tree and plant paradise. A mass of soft yellow drew us from the highway across a field carpeted thickly with bluet or "quaker lady," to the edge of the stream, where a continuous hum showed that the bees were also attracted. It was one splendid willow in full bloom, and I could not and as yet cannot safely say whether it is the crack willow or the white willow; but I can affirm of a certainty that it was a delight to the eye, the mind and the nostrils. The extreme fragility of the smaller twigs, which broke away from the larger limbs at the lightest shake or jar, gave evidence of one of Nature's ways of distributing plant life; for it seems that these twigs, as I have previously said, part company with the parent tree most readily, float away on the stream, and easily establish themselves on banks and bars, where their tough, interlacing roots soon form an almost impregnable barrier to the onslaught of the flood. Only a stone's throw away there stood a great old black willow, with a sturdy trunk of ebon hue, crowned with a mass of soft green leafage, lighter where the breeze lifted up the under side to the sunlight. Many times, doubtless, the winds had shorn and the sleet had rudely trimmed this old veteran, but there remained full life and vigor, even more attractive than that of youth.

Most of the willows are shrubs rather than trees, and there are endless variations, as I have before remarked. Further, the species belonging at first in the Eastern Hemisphere have spread well over our own side of the globe, so that it seems odd to regard the white willow and the weeping willow as foreigners. At Niagara Falls, in the beautiful park on the American side, on the islands amid the toss of the waters, there are many willows, and those planted by man are no less beautiful than those resulting from Nature's gardening. In spring I have had pleasure in some splendid clumps of a form with lovely golden leaves and a small, furry catkin, found along the edge of the American rapids. I wonder, by the way, how many visitors to Niagara take note of the superb collection of plants and trees there to be seen, and which it is a grateful relief to consider when the mind is wearied with the majesty and the vastness of Nature's forces shown in the cataract? The birds are visitors to Goat Island and the other islets that divide the Niagara River, and they have brought there the plants of America in wonderful variety.

There is one willow that has been used by the nurserymen to produce a so-called weeping form, which, like most of these monstrosities, is not commendable. The goat willow is a vigorous tree introduced from Europe, having large and rather broad and coarse leaves, dark green above and whitish underneath. It is taken as a "stock," upon which, at a convenient height, the skilled juggler with trees grafts a drooping or pendulous form known as the Kilmarnock willow, thus changing the habit of the tree so that it then "weeps" to the ground. Fortunately, the original tree sometimes triumphs, the graft dies, and a lusty goat willow rears a rather shapely head to the sky.

This Kilmarnock willow is a favorite of the peripatetic tree agent, and I have enjoyed hugely one notable evidence of his persuasive eloquence to be seen in a Lebanon Valley town, inhabited by the quaint folk known as Pennsylvania Germans. All along the line of the railroad traversing this valley may be seen these distorted willows decorating the prim front yards, and they are not so offensive when used with other shrubs and trees. In this one instance, however, the tree agent evidently found a customer who was persuaded that if one Kilmarnock willow was a good thing to have, a dozen of them was twelve times better; wherefore his dooryard is grotesquely adorned with that many flourishing weepers, giving an aspect that is anything but decorous or solemn. Some time the vigilance of the citizen will be relaxed, it may be hoped; he will neglect to cut away the recurring shoots of the parent trees, and they will escape and destroy the weeping form which provides so much sarcastic hilarity for the passers-by.

The willow, with its blood relation, the poplar, is often "pollarded," or trimmed for wood, and its abundant vigor enables it to recover from this process of violent abbreviation more satisfactorily than do most trees. The result is usually a disproportionately large stem or bole, for the lopping off of great branches always tends to a thickening of the main stem. The abundant leafage of both willow and poplar soon covers the scars, and there is less cause to mourn than in the case of maples or other "hard-wooded" trees.

If my readers will only add a willow section to their mental observation outfit, there will be much more to see and appreciate. Look for and enjoy in the winter the variation in twig color and bark hue; notice how smoothly lies the covering on one stem, all rugged and marked on another. In the earliest spring examine the swelling buds, of widely differing color and character, from which shortly will spring forth the catkins or aments of bloom, followed by the leaves of varied colors in the varied species, and with shapes as varied. Vivid green, soft gray, greenish yellow; dull surface and shining surface above, pale green to almost pure white beneath; from the long and stringy leaf of the weeping willow to the comparatively broad and thick leaf of the pussy-willow—there is variety and interest in the foliage well worth the attention of the tree-lover. When winter comes, there will be another set of contrasts to see in the way the various species lose their leaves and get ready for the rest time during which the buds mature and ripen, and the winter colors again shine forth.

These observations may be made anywhere in America, practically, for the willow is almost indifferent to locality, growing everywhere that its far-reaching roots can find the moisture which it loves, and which it rapidly transpires to the thirsty air. As Miss Keeler well remarks, "The genus Salix is admirably fitted to go forth and inhabit the earth, for it is tolerant of all soils and asks only water. It creeps nearer to the North Pole than any other woody plant except its companion the birch. It trails upon the ground or rises one hundred feet in the air. In North America it follows the water-courses to the limit of the temperate zone, enters the tropics, crosses the equator, and appears in the mountains of Peru and Chili.... The books record one hundred and sixty species in the world, and these sport and hybridize to their own content and to the despair of botanists. Then, too, it comes of an ancient line; for impressions of leaves in the cretaceous rocks show that it is one of the oldest of plants."

Common it is, and therefore overlooked; but the reader may well resolve to watch the willow in spring and summer, with its bloom and fruit; to follow its refreshing color through winter's chill; to observe its cheer and dignity; and to see the wind toss its slender wands and turn its graceful leaves.

The poplars and the willows are properly considered together, for together they form the botanical world family of the SalicaceÆ. Many characteristics of bloom and growth, of sap and bark, unite the two, and surely both, though alike common to the world, are common and familiar trees to the dwellers in North America.

One of my earliest tree remembrances has to do with a spreading light-leaved growth passed under every day on the way to school—and, like most school-boys, I was not unwilling to stop for anything of interest that might put off arrival at the seat of learning. This great tree had large and peculiar winter buds, that always seemed to have advance information as to the coming of spring, for they would swell out and become exceedingly shiny at the first touch of warm sun. Soon the sun-caressing would be responded to by the bursting of the buds, or the falling away of their ingenious outer protecting scales, which dropped to the ground, where, sticky and shining, and extraordinarily aromatic in odor, they were just what a curious school-boy enjoyed investigating. "Balm of Gilead" was the name that inquiry brought for this tree, and the resinous and sweet-smelling buds which preceded the rather inconspicuous catkins or aments of bloom seemed to justify the Biblical designation.

Nearly a world tree is this poplar, which in some one of its variable forms is called also tacamahac, and balsam poplar as well. Its cheerful upright habit, really fine leaves and generally pleasing air commend it, but there is one trouble—it is almost too vigorous and anxious to spread, which it does by means of shoots or "suckers," upspringing from its wide area of root-growth, thus starting a little forest of its own that gives other trees but small chance. But on a street, where the repression of pavements and sidewalks interferes with this exuberance, the balsam poplar is well worth planting.

The poplars as a family are pushing and energetic growers, and serve a great purpose in the reforestation of American acres that have been carelessly denuded of their tree cover. Here the trembling aspen particularly, as the commonest form of all is named, comes in to quickly cover and shade the ground, and give aid to the hard woods and the conifers that form the value of the forest growth.

This same American aspen, a consideration of the lightly hung leaves of which has been useful to many poets, is a well-known tree of graceful habit, particularly abundant in the forests north of Pennsylvania and New Jersey, and occupying clearings plentifully and quickly. Its flowers are in catkins, as with the rest of the family, and, like other poplars, they are in two kinds, male and female, or staminate and pistillate, which accounts for some troubles the inexperienced investigator has in locating them.

There is another aspen, the large-toothed form, that is a distinct botanical species; but I have never been able to separate it, wherefore I do not try to tell of it here, lest I fall under condemnation as a blind leader, not of the blind, but of those who would see!

In many cities, especially in cities that have experienced real-estate booms, and have had "extensions" laid out "complete with all improvements," there is to be seen a poplar that has the merit of quick and pleasing growth and considerable elegance as well. Alas, it is like the children of the tropics in quick beauty and quick decadence! The Carolina poplar, it is called, being a variety of the wide-spread cottonwood. Grow? All that is needed is to cut a lusty branch of it, point it, and drive it into the earth—it will do the rest!

This means cheap trees and quick growth, and that is why whole new streets in West Philadelphia, for instance, are given up to the Carolina poplar. Its clear, green, shining leaves, of good size, coming early in spring; its easily guided habit, either upright or spreading; its very rapid growth, all commend it. But its coarseness and lack of real strength, and its continual invitation to the tree-butcher and the electric lineman, indicate the undesirability of giving it more than a temporary position, to shade while better trees are growing.

But I must not get into the economics of street-tree planting. I started to tell of the blossoms of this same Carolina poplar, which are decidedly interesting. Just when the sun has thoroughly warmed up the air of spring there is a sudden, rapid thickening of buds over one's head on this poplar. One year the tree under my observation swelled and swelled its buds, which were shining more and more in the sun, until I was sure the next day would bring a burst of leaves. But the weather was dry, and it was not until that wonderful solvent and accelerator of growing things, a warm spring rain, fell softly upon the tree, that the pent-up life force was given vent. Then came, not leaves, but these long catkins, springing out with great rapidity, until in a few hours the tree glowed with their redness. A second edition of the shower, falling sharply, brought many of the catkins to the ground, where they lay about like large caterpillars.

The whole process of this blooming was interesting, curious, but hardly beautiful, and it seemed to fit in with the restless character of the poplar family—a family of trees with more vigor than dignity, more sprightliness than grace. As Professor Bailey says of the cottonwood, "It is cheerful and restive. One is not moved to lie under it as he is under a maple or an oak." Yet there are not wanting some poplars of impressive character.

One occurs to me, growing on a wide street of my home town, opposite a church with a graceful spire. This white or silver-leaved poplar has for many years been a regular prey of the gang of tree-trimmers, utterly without knowledge of or regard for trees, that infests this town. They hack it shamefully, and I look at it and say, "Well, the old poplar is ruined now, surely!" But a season passes, and I look again, to see that the tremendous vigor of the tree has triumphed over the butchers; its sores have been concealed, new limbs have pushed out, and it has again, in its unusual height, assumed a dignity not a whit inferior to that of the church spire opposite.

This white poplar is at its best on the bank of a stream, where its small forest of "suckers" most efficiently protects the slope against the destructive action of floods. One such tree with its family and friends I saw in full bloom along the Susquehanna, and it gave an impression of solidity and size, as well as of lusty vigor, and I have always liked it since. The cheerful bark is not the least of its attractions—but it is a tree for its own place, and not for every place, by reason of the tremendous colonizing power of its root-sprouts.

I wonder, by the way, if many realize the persistence and vigor of the roots of a tree of the "suckering" habit? Some years ago an ailanthus, a tree of vigor and beauty of foliage but nastiness of flower odor, was cut away from its home when excavation was being made for a building, which gave me opportunity to follow a few of its roots. One of them traveled in search of food, and toward the opportunity of sending up a shoot, over a hundred feet!

The impending scarcity of spruce logs to feed the hungry maws of the machines that make paper for our daily journals has turned attention to several forms of the rapid-growing poplar for this use. The aspen is acceptable, and also the Carolina poplar, and these trees are being planted in large quantities for the eventual making of wood-pulp. Even today, many newspapers are printed on poplar, and exposure to the rays of the truth-searching sun for a few hours will disclose the yellowness of the paper, if not of the tree from which it has been ground.

Few whose eyes are turned upward toward the trees have failed to note that exclamation-point of growth, the Lombardy poplar. Originating in that portion of Europe indicated by its common name, and, indeed, a botanical form of the European black poplar, it is nevertheless widely distributed in America. When it has been properly placed, it introduces truly a note of distinction into the landscape. Towering high in the air, and carrying the eye along its narrowly oval contour to a skyward point, it is lofty and pleasing in a park. It agreeably breaks the sky-line in many places, and is emphatic in dignified groups. To plant it in rows is wrong; and I say this as an innocent offender myself. In boyhood I lived along the banks of the broad but shallow Susquehanna, and enjoyed the boating possible upon that stream when it was not reduced, as graphically described by a disgusted riverman, to merely a heavy dew. Many times I lost my way returning to the steep bluff near my home after the sun had gone to rest, and a hard pull against the swift current would ensue as I skirted the bank, straining eyes for landmarks in the dusk. It occurred to me to plant six Lombardy poplars on the top of the bluff, which might serve as easily recognized landmarks. Four of them grew, and are now large trees, somewhat offensive to a quickened sense of appropriateness. Long since the old home has been swallowed up by the city's advance, and I suppose none who now see those four spires of green on the river-bank even guess at the reason for their existence.

The poplar family, as a whole, is exuberant with vigor, and interesting more on that account than by reason of its general dignity or strength or elegance. It is well worth a little attention and study, and the consideration particularly of its bloom periods, to which I commend the tree-sense of my readers as they take the tree walks that ought to punctuate these chapters.