Among Scottish foresters the name "plane-tree" has come to signify the sycamore; but the sycamore is a kind of maple, whereas the term "plane" is rightly appropriated to Platanus, whereof there are four species, constituting the natural order of PlatanaceÆ. Of these four species, three are natives of North America; and forasmuch as none of them has proved amenable to cultivation in Europe, they may be dismissed with the remark that one of them, the button-wood (P. occidentalis), attains enormous proportions in its native forests, rising to a height of 170 feet, and with a girth (recorded by Michaux) of 47 feet.

The fourth species (P. orientalis) ranks among the noblest hardwoods of temperate Europe and Asia. Clear among memories of many sylvan scenes stand a pair of giant planes on the flank of Mount Olympus, in the leafless branches of which on a bright January morning a pair of white-tailed eagles monopolised the attention which I was intended by my Turkish host to devote to woodcocks in the copse below. Those who have sailed along the Dalmatian coast will doubtless remember the harbour of Gravosa, and the solitary plane that casts such a grateful shade across the quay. But one need not go to the Continent for giant planes. In our day it is one of the trees most commonly planted in the southern counties for shade and ornament, and has no equal for the smoke-laden atmosphere of London. It may be that it was one of Evelyn's seedlings that Bishop Gunning planted in his Garden at Ely between 1674 and 1684. This tree in 1903 was 104 feet high, with a girth of 20½ feet. Messrs. Elwes and Henry give a photograph of it in their Trees of Great Britain and Ireland, and consider it to be the largest specimen in our islands of the cut-leaved variety.

Turner, writing in 1562, mentions "two very young trees" growing in England, which indicates the middle of the sixteenth century as the period of its introduction. A hundred years later, Evelyn says he has raised from seed—

"Platanus, that so beautiful and precious tree so doated on by Xerxes that Ælian and other authors tell us he made halt and stop'd his prodigious army of seventeen hundred thousand soldiers to admire the pulchritude and procerity of one of these goodly trees, and became so fond of it that he cover'd it with gold gemms, necklaces, scarfs and bracelets, and infinite riches."

The maple-leaved variety, usually known as the London plane, is the sort most commonly planted in England, and rightly so, for it is more vigorous than the other. Probably the tallest in England grows at Woolbeding, in Sussex; it was 110 feet high in 1903, with a girth of 10 feet, and a clean bole of 30 feet. It would be needless to enumerate the fine planes in and near London; one has only to look at the groups beside the Admiralty and in Berkeley Square to realise how it thrives in an atmosphere pernicious to nearly all other forest growths. Fifty or sixty years hence the avenue of planes planted not long since along the Mall will be one of the sights of Europe. The skilful way in which they are being trained each to a single leader gives them a stiff, ungraceful appearance at present; but this treatment is a bit of true arboriculture, carried out in the teeth of bitter criticism. "Bairns and fules shouldna see things half dune."

It is the absence of the conditions specially favourable to the growth of the plane in London and the south that makes it unsuitable for planting in the North of England and in Scotland. It is native to a region of scorching summers; in London the sun's heat is reflected from buildings and streets in a manner most acceptable to it. It will stand any amount of frost it may encounter in Scotland; but it pines for want of summer heat, witness the unhappy condition of those which have been planted experimentally along the west end of Princes Street, Edinburgh. I do not know of a single plane of more than mediocre stature north of the Tweed.

The plane is nearly as late in leafing as the ash and the walnut, thereby escaping the cruel frosts so characteristic of British spring; but unlike the ash, it retains its foliage into very late autumn. Pliny described an evergreen plane growing in Crete; but after the botanist Tournefort (1656-1708) had searched the island in vain for it, this was relegated to the category of myths. Howbeit, tardy justice was done to Pliny as the prince of field naturalists, when in 1865 Captain Spratt, R.N., was shown two young plane trees, retaining their leaves throughout the winter, which had sprung from the root of a very large tree that had been felled. He also heard of two others.

The Oriental plane has not been long enough established with us to give an estimate of its longevity in Britain. In the Mediterranean region it attains a vast age. Only a hollow stump remains of one at Vostiza, in the Gulf of Lepanto, which in 1842 was about 130 feet high and 37 feet 4 inches in girth, and was believed to be the tree described by Pausanias when writing his description of Greece in the second century after Christ. Neither have we learnt to make much use of the timber so plentifully produced by the plane, though it is said to be second to none for the bodies of carriages.

In antiquity of descent the plane tree has few, if any, superiors among broad-leaved trees, its remains having been recovered from the Cretaceous beds of North America, besides numerous species recovered from Miocene and Tertiary strata, in Northern Europe, whence they were expelled when that region became icebound.

The London planes have been accused of being chief agents in inflicting influenza, bronchitis and catarrh upon the inhabitants of the metropolis. It has been seriously affirmed that when the seed-vessels of the plane break up in dry spring weather, the air is filled with minute spicules which act as an irritant upon human throats and noses. It may be so; but before condemning the trees, without which London would indeed be desolate, it would be well to ascertain first whether the ailments referred to are more prevalent in London during the months when the plane tree is shedding its dry fruit than they are at other times of the year; and second, whether they are more prevalent in London, where there is wealth of planes, than they are in cities where there are no planes, as Edinburgh, Glasgow, Liverpool, Newcastle, etc. Unless this can be shown to be the case, it is difficult to reconcile the fact that London has the lowest death-rate among the cities of the United Kingdom with any mischief arising from the luxuriance of these beautiful trees.