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A medium-sized tree, its lower branches horizontal, the upper usually ascending, but sometimes spreading on old specimen trees, forming a rounded or broadly oblong crown; bark on young trees brown, whitish or yellowish when first exposed, but not flaking freely and ceasing to do so earlier than in the London plane, and soon becoming rugged. Leaves rich green and glossy, mostly 6 to 7 in. wide, with usually three, more rarely five, rather short and broad, sparsely toothed lobes, truncate or shallowly cordate at the base, with or without a central wedge, main veins arising at or not much above the junction of the blade with the petiole. Although three female inflorescences may be produced on each peduncle, only one or two develop; solitary fruit-heads are perhaps the commoner, and are unusually large – about 13⁄4 in. across.
This plane was apparently raised (or first distributed) in France or Belgium, and was introduced to Britain about 1850. The epithet pyramidalis must have been attached to it when only young plants were known, since mature, untreated trees are broad-crowned. But if the lower, horizontal branches are removed the tree becomes vase-shaped. The trees in Vincent Square, London, opposite the Old Hall of the Royal Horticultural Society, are ‘Pyramidalis’, and show the characteristic habit very well. The one immediately opposite the main entrance appears in a photograph taken in 1904; it was then bushy and perhaps twenty years old (Gard. Chron., Vol. 36, fig. 30). The docility with which ‘Pyramidalis’ accepts the removal of its lower branches, and its excellent response even to the crudest lopping, no doubt explains why it has become so common in streets and other line-plantings. But often it can be found planted in mixture with the London plane, with which it has been confused. A notable example is the Broad Walk in Green Park, London, between Piccadilly and the Queen Victoria Memorial, where the double lines on each side are made up of the two clones in mixture, ‘Pyramidalis’ being easily picked out even in winter, owing to its darker, more rugged bark and straighter branches. The specimen in Green Park planted by King George V and Queen Mary in 1911 is ‘Pyramidalis’. It measures 75 × 93⁄4 ft (1968).
‘Pyramidalis’ is quite near to P. occidentalis, under which it was placed by Jaennicke. The fruit-balls are more bristly than in that species, and the achenes have hairs on the body as well as at the base, but in other respects it shows no sign of the influence of P. orientalis. From the London plane, of which Henry supposed it to be a seedling, it is distinct in its glossy leaves rarely more than shallowly cordate at the base and with a broader central lobe; also by the often solitary, very large fruit-balls and the quite different habit and bark. It is easily propagated by cuttings.
The P. densicoma of Dode appears to be based partly on ‘Pyramidalis’, partly on P. occidentalis var. glabrata.