Trees & Shrubs – Platanus / Plane trees, inc’ Platanus × acerifolia The London Plane Tree.
Platanus /ˈplætənəs/ is a genus comprising a small number of tree species native to the Northern Hemisphere. They are the sole living members of the family Platanaceae.
All members of Platanus are tall, reaching 30–50 m (98–164 ft) in height. All except for P. kerrii are deciduous, and most are found in riparian or other wetland habitats in the wild, though proving drought-tolerant in cultivation. The hybrid London Plane has proved particularly tolerant of urban conditions.
They are often known in English as planes or plane trees. Some North American species are called sycamores (especially Platanus occidentalis), although the term sycamore also refers to the fig Ficus sycomorus, the plant originally so named, and to the Sycamore Maple or False Plane Acer pseudoplatanus.
Platanus × acerifolia, London plane, London planetree, or hybrid plane, is a tree in the genus Platanus. It is usually thought to be a hybrid of Platanus orientalis (oriental plane) and Platanus occidentalis (American sycamore). Some authorities think that it may be a cultivar of P. orientalis.
The London plane is a large deciduous tree growing 20–30 m (66–98 ft), exceptionally over 40 m (131 ft) tall, with a trunk up to 3 m (10 ft) or more in circumference. The bark is usually pale grey-green, smooth and exfoliating, or buff-brown and not exfoliating. The leaves are thick and stiff-textured, broad, palmately lobed, superficially maple-like, the leaf blade 10–20 cm (4–8 in) long and 12–25 cm (5–10 in) broad, with a petiole 3–10 cm (1–4 in) long. The young leaves in spring are coated with minute, fine, stiff hairs at first, but these wear off and by late summer the leaves are hairless or nearly so. The flowers are borne in one to three (most often two) dense spherical inflorescences on a pendulous stem, with male and female flowers on separate stems. The fruit matures in about 6 months, to 2–3 cm diameter, and comprises a dense spherical cluster of achenes with numerous stiff hairs which aid wind dispersal; the cluster breaks up slowly over the winter to release the numerous 2–3 mm seeds.
It shares many visual similarities with Platanus occidentalis (American sycamore), of which it is derived; however, the two species are relatively easy to distinguish, considering the London plane is almost exclusively planted in urban habitats, while P. occidentalis is most commonly found growing in lowlands and alluvial soils along streams in its native North America.
Over a century ago the English horticulturist Edward Step had this to say about the Plane Tree, amazingly he foretold the take over of the London Plane.
The Plane (Platanus orientalis).
In spite of the fact that the Plane is an exotic of comparatively recent introduction, it seems in a fair way of being associated in the future with London. It has taken with great kindness to London life, in spite of the drawbacks of smoke, fog, flagstones, and asphalt.
Its leaves get thickly coated with soot, which also turns its light-grey bark to black; but as the upper surface of the leaves is smooth and firm, a shower of rain washes them clean, and the rigid outer layer of bark is thrown off by the expansion of the softer bark beneath. This is not thrown off all at once, but in large and small flakes, which leave a smooth yellow patch behind, temporarily free from soot contamination. A variety of trees has been tried for street-planting, but none has stood the trying conditions of London so well as the Plane, and therefore before many years the capital will be the city of Planes.
Bole of Plane Tree.
Two species are recognized—the Oriental Plane (Platanus orientalis) and the Western Plane (P. occidentalis); but it would probably be more accurate to regard them as geographical varieties of one species, the points in which they differ being small and not very important. Thus the leaves of the Oriental Plane are described as being so much more deeply lobed than those of the Western Plane that the former are botanically described as palmate; but the two forms of leaf may often be found on the same individual. The Western Plane, too, does not shed its bark in small flakes like the Oriental Plane, but in large sheets.
Planes normally rise to a height of something between seventy and ninety feet, and the trunk attains a circumference of from nine to twelve feet; but there is a record of a portly Plane whose waist measurement was forty feet! Many persons imagine because the leaves of the Plane resemble those of the Sycamore that the two are closely related; but this is not so, and a comparison of the flowers and fruit will show that they are not. The catkins of the Plane take the form of balls, in which male or female flowers are pressed together; and the fruits, instead of being winged samaras, are the rough balls that so closely resemble an old-fashioned form of button, that the tree is known in some parts of the United States as the Button-wood. (It is also known there as Sycamore and Cotton-tree.)
The Plane is supposed to have got its name Platanus from the Greek word platus (broad), in double allusion to the broad leaves and the ample shadow which the tree throws. These leaves are five-lobed, and, as already indicated, those of the Oriental species are much more deeply cut. Further distinction is found in the colour of the petiole or leaf-stalk, which is green in P. orientalis, and purplish-red in P. occidentalis, and in the larger and smoother seed-buttons of the latter. Instead of the leaves being attached to the stem in pairs, as we saw in the Sycamore, those of the Plane are alternate—that is to say, leaf number two of a series will be halfway between one and three, but on the opposite side of the shoot.
The outline of the tree is not so regular as in most others, the leaves being gathered in heavy masses, with broad spaces between, rather than equally distributed over the head. This is, of course, due to the freedom with which the crooked arms are flung about. The pale-brown wood is fine-grained, tough, and hard, and is extensively used by pianoforte-makers, coach-builders, and cabinet-makers, but is not highly esteemed for other purposes to which timber is put in this country.
The Oriental Plane is popularly supposed to have been introduced to England from the Levant by Francis Bacon, but if Loudon’s statement that it was “in British gardens before 1548” rests on good evidence, Bacon’s claim is dismissed, for he was not “introduced” until 1561. It was nearly a hundred years later (1640) that the Occidental Plane was first brought from Virginia by the younger Tradescant, and planted in that remarkable garden of his father’s in South Lambeth Road. The form that has done so well in London, and of which many fine examples are to be seen in the parks and squares, is a variety of the Oriental Plane, with leaves less deeply divided than those of the type, and therefore more nearly approaching the Occidental Plane in this respect. It is distinguished by the name of the Maple-leaved Plane (Platanus orientalis, var. acerifolia). It is this variety we have chosen as the subject for our photograph.