Part 6

The true meaning of the prefix "horse," by which this tree is distinguished from the true or Spanish chestnut, has been the subject of much discussion. Apparently it was not applied in the sense of "coarse, large," as in the terms horse-radish, horse-mushroom, etc., for the Turkish name for it is _at kastan_, signifying horse-chestnut; and this was explained in a letter written by the Flemish Dr. Quackleben to Matthiolus in 1557 (many years before the tree was known in Britain), explaining the use of the fruit as a specific against broken wind in horses.

The Poplars

"Hard by a poplar shook alway, All silver green with gnarled bark; For leagues no other tree did mark The level waste, the rounding gray."

There is much confusion among the different species of poplar, but it is clear that in these verses Tennyson had in view our native abele or grey poplar (_Populus canescens_), a native of Great Britain, often mistaken for the white poplar (_P. alba_), which nearly resembles the grey, and has been planted in this country, but is probably an exotic. The poet's epithet "silver green" admirably describes the foliage of the grey poplar, for some of the shoots bear green leaves, others white ones, others again green leaves on the lower part and white on the upper.

Of all known species of poplar, thirty or so in number, the abele produces the choicest timber, much in request by carriage-builders, who sometimes pay as much as 2s. 6d. a cubic foot for well-grown logs. It is excellent timber for flooring bedrooms, being less inflammable than any other British-grown wood except larch. It is, therefore, characteristic of British neglect of woodland resources that this tree is hardly ever planted, though it is most easily propagated from suckers or cuttings, and attains an immense size long before an oak could reach maturity.

The abele is more common in Scotland than in England, and many large trees might be mentioned in the North. It would be difficult, however, to find any to surpass two growing at Mauldslie Castle, in Clydesdale, one of which in 1911 measured 100 feet high and 21 feet 3 inches in girth, the other 117 feet by 16 feet 5 inches. It should be noted that the girth of both was taken at between 2 and 3 feet from the ground, instead of 5 feet, which is the proper height for measurement.

Next in economic importance to the grey poplar stands what is popularly known in this country as the black Italian poplar (_P. serotina_), which is not Italian in any sense, but a hybrid originating in France (where it is called _peuplier suisse_) between an American species and the true black poplar (_P. nigra_). This confusion of names is all the more perplexing because the upright variety of the true black poplar goes by the name of Lombardy poplar. However, one must use the names most generally recognised among woodmen, and the black Italian poplar is well worthy of more attention than it has hitherto received in this country, for it produces valuable timber in greater bulk in a short term of years than any other British-grown tree. Mr. Elwes has recorded how thirty poplars of this variety, planted on cold clay in Gloucestershire, not worth 5s. an acre, were sold for £3 apiece at forty-eight years of age. He lays stress on the importance of giving this tree plenty of room at all stages of growth, planting them at 15 to 20 feet apart, for the timber is little worth unless the tree gets enough light to enable it to produce wood rapidly. This precept applies to every species of poplar.

The tallest black Italian poplar in Great Britain is probably one growing on the banks of the Tillingbourne, in Albury Park, Surrey, which in 1912 measured 150 feet high, with a girth of 15 feet 3 inches. There are many fine specimens in Scotland, notably one at Scone Palace, which in 1904 was 132 feet high, with a girth of 15 feet 4 inches. Another at Monzie, in Perthshire, measured at the same time, stood 125 feet high.

Turning now to the true black poplar (_Populus nigra_), we find that this species, a native of Midland England, but probably not of Scotland, has become established in the eastern United States, having been introduced there by British colonists. It has often been confused with the black Italian variety, but may easily be distinguished in this country by the large burrs on the trunk, by its earlier leafing, and by the young foliage being green, instead of reddish, as in the black Italian. The true black poplar also sheds its leaves much earlier in autumn than does the other. It is not a tree commonly planted in Scotland, but there are specimens ranging from 90 to 100 feet high at Dalzell, Ross, and Cambusnethan, in Lanarkshire; at Auchentorlie, on the Clyde; and at Smeaton-Hepburn, in East Lothian.

The variety of this tree so well known as the Lombardy poplar forms a notable feature in the landscapes of Southern England, Central and Southern Europe, and a great part of Asia. As it can only be propagated by cuttings, it is believed that all the millions of Lombardy poplars spread over the continents of Europe and Asia originated with a single "sport" growing on the bank of the river Po early in the eighteenth century. Probably the first of its race was brought to England about 1750 by the third Duke of Argyll, and planted by him at Whitton, near Hounslow. This tree, which has now disappeared, was measured by Loudon before 1838 as 115 feet high.

One peculiarity of the Lombardy poplar I do not remember to have seen noticed by any writer on forestry. Other poplars of all sorts, including the black poplar whereof this is only a variety, mingle branches freely with their neighbours; but the Lombardy poplar is a regular _Sainte-Nitouche_, and will not suffer contact with any other tree, even one of its own race. A curious example of this may be seen in London. When the Buckingham Palace Hotel was built, somewhere about 1860, Queen Victoria desired that a screen of trees should be planted within the Palace enclosure to shut the hotel out of view. The Office of Works chose the Lombardy poplar, calculating that it would form a lofty, thick hedge. Not a bit of it! The trees died rather than touch each other; they have been replaced times without number; but the Office of Works has never discerned the secret of their temperament, and continue their task of Sisyphus year after year, filling the gaps caused by death with trees of the same kind. Had a row of true planes been set there at first, the privacy of the Palace would have been secured long before this.

Despite this constant characteristic of the Lombardy poplar, which anybody may verify for himself by examining the fine groups of them near Maidenhead and Windsor, Selby committed himself to the extraordinary statement that this tree, "planted so as to form a hedge, and being cut even at a certain height and regularly trimmed, becomes a thick and verdant hedge."[11]

The asp (_Populus tremula_) is now generally spoken of by the adjectival form "aspen." Its ceaseless movement earned it the name of "quick-beam" in Anglo-Saxon, and the Lowland Scots name, "quakin' asp" (corrupted into "quakin' ash") has, so far, survived the operations of School Boards. Long may it do so! The same characteristic in this tree gave it the Gaelic name of _crithean_ (creean) or _criothach_ (creeagh), "the trembler," which may be recognised in such place-names as Creechan in Dumfriesshire and, perhaps, Crieff, in Perthshire. Although in bulk and stature one of the humbler members of the poplar family, the asp exhibits in an extreme form a peculiarity common to all the genus--namely, that of hanging the leaves vertically, instead of holding them horizontally. The leaves are glandular on both surfaces, which may be either the effect of or the reason for their assuming a position protecting both surfaces from the direct rays of the sun. To secure this position, the petiole, or foot stalk, of each leaf, being cylindrical in most of its length, is suddenly flattened midway between the leaf and the twig, as if it had been pinched while soft. This causes the leaf to hang as described, and to quiver with the slightest breath of air.

The asp is a hardy mountaineer; its graceful foliage and _eau-de-Nile_ bark saves many a Highland hillside from dreariness, but it has long ceased to have the economic importance it once had. By an Act of the English Parliament (4 Henry V. c. 3), a penalty of 100 shillings was imposed upon anyone who put aspen wood to any other purpose than the making of arrows. Mrs. Hemans has woven into verse the mediæval myth which taught men to reckon this pretty tree accursed:

Oh! a cause more deep, More solemn far, the rustic doth assign To the strange restlessness of those wan leaves. The cross, he deems, the blessed cross whereon The meek Redeemer bowed His head to death, Was formed of aspen wood; and since that hour Through all its race the pale tree hath sent down A thrilling consciousness, a secret awe, Making them tremulous, when not a breeze Disturbs the airy thistle-down, or shakes The light lines of the shining gossamer.

Gerard, writing in the sixteenth century, says, with scant gallantry, that the asp "may also be called _tremble_ after the French name, considering it is the matter whereof women's toongs were made, which seldom cease wagging."

Professor Sargent enumerates eleven species of poplar as indigenous to North America, some of which, such as the Balsam poplar (_P. balsamifera_), the Ontario poplar (_P. candicans_), and the Carolina poplar (_P. angulata_), have risen to large dimensions in British woodland; but to follow out these, and their constantly recurring hybrids, would far exceed the limits of this paper.

There are many Asiatic species also, one of which (_P. euphratica_) we are now taught to recognise as the "arabim" whereon the captive Jews hung their harps (Psalm cxxxvii. 2). The weeping willow, named by Linnæus _babylonica_, is not found in the valley of the Euphrates.

It is time that British planters should recognise the importance of the more vigorous species of poplar as rapid timber-producers, thriving in cold, wet ground where no other crop could be raised so successfully. A useful example is set in this matter by French cultivators, who plant more poplars than any other tree. Moreover, all the species are most easily propagated and handled in planting. They should be grown from cuttings; it is futile to attempt raising them from seed--a most uncertain process, and unsatisfactory when it succeeds, cutting-grown plants being far more vigorous than seedlings.

The Birch

Bentham and Hooker recognised only two species of birch as indigenous to the British Isles--namely, _Betula alba_, the common birch, and _B. nana_, an insignificant shrub which grows in the Scottish Highlands. Messrs. Elwes and Henry, however, in their great work give specific rank to each of the two forms of the common birch prevailing in this country. It is certainly strange that the difference between them has not received more attention from foresters, seeing that one is a far more valuable tree than the other. Whether they be permanent species or merely racial varieties matters not for practical purposes; but it matters much that the better kind be planted where conditions are favourable for it.

The commoner and less desirable of the two forms has been named _B. pubescens_, owing to the young shoots being clothed with down, sometimes so minute as to require a lens to show it. This and the habit of the tree are the only constant marks of distinction from the other form, which is named _B. verrucosa_, because the shoots, though shining and perfectly free from down, are studded with minute _verrucæ_, or warts, easily discernible by the naked eye. I have found in southern Norway, where the two reputed species grow together, intermediate forms which are no doubt natural hybrids.

The two species are usually quite different in habit, the common birch (_B. pubescens_) never carrying the long pendulous branchlets which distinguish the silver birch (_B. verrucosa_). Moreover, the common birch does not usually attain the stature of the other, although Mr. Elwes mentions having measured one at Malborough 90 feet high, with a girth of 8 feet. This is the species which grows naturally over the greater part of Scotland, especially in the west and north. The distinctive downiness of the young twigs may have had its origin in the humid atmosphere and abundant rainfall of the regions where it most abounds. Geographically it enjoys a very wide range, extending farther north than any other tree--as far as latitude 71° near the North Cape--and reappearing in Iceland and southern Greenland, far within the limit of floating ice. Eastward it extends as far as Kamschatka, but it does not reach southward beyond the Alps, not being found in the Pyrenees or the Apennines, whereas the silver birch reaches down to Sicily.

Coming to the north-east of Scotland, to Strathspey, Deeside, and part of the basin of the Moray Firth, one finds a change in the aspect of the birch forest; for here, although the common birch still prevails on the wetter parts, the silver birch is dominant on the drained land and hill sides. It is there that the lady of the woods displays her true grace and it is hard to say whether she is more lovely in summer, when she waves her long green tresses in the breeze, or in winter, when the slanting sunbeams glint on the snowy stem, and the drooping branchlets appear like fine tracery against the sky. This is the true weeping birch so highly prized by landscape gardeners, and this is the species that should always be chosen for planting, provided the land is well drained, for it cannot stand damp feet with the same impunity as its cousin. The general rule is not difficult to remember that, whereas the common or downy birch will grow on almost any soil that is not actual swamp, the silver or weeping birch is very impatient of stagnant moisture.

Beautiful as are the birch woods of Strathspey (travellers to the North must have been charmed with those on both sides of the railway near Lochinsch Station), it must be confessed that the silver birch does not attain its greatest perfection in Great Britain. Individual trees may be found to compare pretty well with those in Continental woods; but the general average is not so good. I have not seen the birch forests of the Baltic provinces and Central Russia; those who have done so speak enthusiastically of them; but it is from no want of loyalty to the Birks of Aberfeldy that I have to admit that their bark has not the sheen nor their growth the free grace of their kindred in French, German, and Scandinavian forests.

Inseparably associated as the birch is with Scottish landscape, poets and painters have never wearied of honouring it. The late David MacWhirter got its beauty rather on the brain, and one turned rather tired of what became a mannerism in his work. Hamilton of Bangour never rang his quaintly iterative changes so tenderly as in his ballad, _The Braes of Yarrow_, the tragedy of a maiden with two lovers. The lovers fight, and one falls--

The comliest swain That e'er pu'd birks on the braes o' Yarrow.

The survivor presses his court, trying in vain to persuade the girl to leave Tweedside and come to his home beside Yarrow.

Sweet smells the birk, green grows, green grows the grass-- Yellow on Yarrow's braes the gowan; Fair hangs the apple frae the rock, Sweet the wave of Yarrow flowin'.

"Flows Yarrow sweet?" she argues with him--

Flows Yarrow sweet? as sweet, as sweet flows Tweed; As green its grass, its gowan as yellow; As sweet smells on its braes the birk, The apple frae its rock as mellow.

The late Professor Veitch laid finger on the only blot in this fair picture. Apples do not hang from rocks either in Tweedside or by Yarrow, but rowan berries do. It is a pity that Hamilton yielded so far to eighteenth century classicism as to introduce the conventional apple. The line would surely have run more smoothly--

"Fair hangs the rowan frae the rock."

But I have wandered away from the birch. Economically, this tree has hitherto been reckoned of indifferent value, though there is an inexhaustible demand for bobbins. Clogmakers, also, will make picturesque encampment among birches of suitable size, and pay a fair price for working up the stems.

Of the well-nigh imperishable bark no use is made in this country, except that chemists extract from it an antiseptic called pyrobetulin, used also in the preparation of glass for engraving. But Scandinavian farmers sheath their wooden houses with birch bark, which makes a durable, waterproof covering, with a beautiful silvery appearance very gratifying to eyes offended by the evil aspect of corrugated iron. In Russia, also, a fragrant oil is distilled from birch-wood, whence Russia leather derives its peculiar odour. Careful housewives should note that there is no kindling equal to birch bark, which blazes up almost as fiercely as celluloid.

Of late years, a new use has been found for birch, deserving attention from owners of land whereon this tree grows naturally. The small branches and spray are found serviceable in the preparation of steel plates, the price given at present being about 46s. a ton. The trees should be cut before the sap rises, else the bundles will lose weight in drying. In dealing with a birch wood for this purpose, the crop may be considered recurrent at short rotation; for numerous suckers arise from the roots after the tree is felled and grow very rapidly. It is to be noted with satisfaction that the well-nigh omnivorous rabbit cannot digest the young growths of birch; at least, it does not devour them wholesale.

The birch is very impatient of the shade of other trees. In its turn, although its delicate foliage might not be supposed to stop much light, its shade is very injurious to all other deciduous trees except the beech; a quality which causes one to wonder that such an experienced observer as P. J. Selby should have recommended it as a nurse for oak.[12] It is liable to be disfigured by the morbid growths popularly known as "witch's brooms." Authorities differ as to the cause of these fascinated bundles of twigs, some attributing them to the action of a fungus, _Exoascus betulinus_, others to the irritation brought about by a gall-mite (_Eriophes rudis_) attacking the buds. Probably both are contributory agents.

The Gaelic for birch is _beith_ (pronounced "bey"), and may be recognised in numberless Scottish place-names, such as Drumbae, Auchenvey, Largvey, etc. The derivative _beitheach_ (pronounced "beyoch"), signifying a birch wood, appears as Beoch in Ayrshire, Galloway, and Dumfriesshire.

Of exotic birches suitable for cultivation in the United Kingdom, there is a very complete collection in Kew Gardens. Among the North American species the black or cherry birch (_Betula lenta_) probably produces the best timber, but the most ornamental is the paper birch (_B. papyrifera_). The Japanese (_B._ _maximowicsii_) seems to promise better bulk than any other as a forest tree in this country.

The Willows

"I offered him my company to a willow-tree, either to make him a garland, as being forsaken, or to bind him up a rod, as being worthy to be whipped."--_Much Ado About Nothing_, Act ii. sc. i.

"Willows whiten, aspens quiver, Little breezes dusk and shiver Through the wave that runs for ever By the island in the river Flowing down to Camelot." _The Lady of Shallot._

A certain botanist of distinction being consulted by an amateur about some variety of willow exclaimed: "Pray, don't tempt me among the willows; that way lies madness!" They are, indeed, a most complex family, consisting of no fewer than one hundred and sixty recognised species, besides those chance hybrids which, being not only wind-fertilised, but dioecious (that is, the male and female inflorescence is borne on separate trees), they are so prone to produce. Bentham and Hooker admitted fifteen species as indigenous to the United Kingdom, ranging from _Salix herbacea_, dwarfest of British shrubs, humbly crouching on bleak mountain crests and seldom rearing its fairy branchlets to a greater height than a couple of inches, to the massive white willow (_S. alba_), which may tower to the height of nearly 100 feet.

British foresters have not hitherto turned the capabilities of the better kinds of willow to such account as might be done, for, except in the osier industry and for the manufacture of cricket bats, willows are scarcely ever cultivated for profit. When they are planted at all they are generally shoved into some piece of sour, swampy ground, fit for nothing else; and the fact that they will actually flourish in such places is taken as evidence that they prefer them. But the better willows appreciate a kindly soil as much as any other tree, and it is only on wholesome, but moist, land that they develop their proper qualities.

By far the most valuable willow in the present condition of the timber market is the blue willow, which some botanists distinguish as a species under the name of _Salix coerulea_, but which is more generally deemed to be a hybrid between the white willow (_S. alba_) and the crack willow (_S. fragilis_). It is easily distinguished from both its reputed ancestors; first, by its habit, which is far more erect than that of the others, all the branches ascending without any tendency to spread or droop; second, by its leaves, which are not nearly so downy as those of the white willow, and of thinner texture, so that, when one is held up against the light the tertiary venation may be seen through a lens to be translucent; and, third, by the bark, which is quite different from the rugged covering of the crack willow, and much smoother than that of the white willow. The fissures or seams in the bark are straight and set close together, enabling one to distinguish the blue willow from all other kinds at all seasons. The general tone of the foliage is silvery blue, instead of the silvery grey of the white willow.