|Plane trees of London
Platanus x acerifolia 'Pyramidalis'
This may be the commonest variety of plane in London. Trees of all ages can be found in parks, as roadside trees, and in modern landscaping plantings. It is the tree normally supplied by nurseries as the 'London plane', and as Platanus acerifolia.
Despite the name, it is only pyramidal in shape when young, and then it is a broad pyramid. It is not columnar, upright or fastigiate, as is sometimes expected from the name. Mature trees are usually spreading, and they are not as tall growing as other varieties. The trunks can however reach a great girth.
Trees are variable, and it is unlikely to be a single clone. The variety seems to merge into a group of 'non-descript' trees, of poor shape. It is possible that the shapes and appearance are influenced by soil or other growth factors.
The following accounts are based on the trees in double avenue in Green Park. These trees were used as an example of the form in Bean's Manual. Numerous other specimens can be found in the capital, though they may become confused with other varieties.
Bark - While the bark flakes as with other planes, it sometimes happens less frequently on the trunk and other oldest wood; this results in the bark becoming rugged, collecting dirt and appearing darker than the crown of the tree. The bark is also often especially thickened, dark and rugged below the point where branches join the trunk. Formation of thickened and rugged bark can also be seen sometimes on the underside of larger branches.
Trunk - On mature trees, the trunk is often irregularly shaped. Some fluting may occur, and a number of irregularities can occur. These may be due to junctions with branches that have been removed. Sometimes in the oldest trees, fluting can be followed into the trunk down from the major branches, and up from the major roots.
Crown - The branches tend to be straighter in comparison with most other planes, and the branching is angular. Young trees have a broad pyramidal shape until lower branches are removed. Mature trees often have many major limbs radiating upwards from a point between 2 to 4 meters above ground. Sometimes they look as if they have been pollarded when young.
Shoot and young leaves - These are covered in down as in all planes, shed on mature tissue. Stipules are shed early during growth. The leaves are moderately affected by anthracnose and many early leaves are damaged by this in London.
Leaf shape - Leaves are commonly seen with 3-5 palmate lobes, with the central lobe usually as long as wide, with a few teeth. The leaf size on typical leaves can be 15 to 18cm wide and long. The tips of the lobes are often turned upward.
Leaf colour - This is usually a dark glossy green above, paler below, and not as glossy as the upper surface. The leaf colour and sheen can often be used to tell the tree at a distance.
Axillary buds - These are typically 7-9mm across at the base, 9-12mm long, conical to ovoid with a blunt tip. They are green after leaf fall, the bud becoming purple on exposure to light. Terminal buds are longer, up to 13 mm long, and with a rounded tip.
Fruits - Flowers and fruit are borne in groups of 1-2 on a stem on short lateral growths, and they can be up to 40 mm across.
The appearance of the trees can be variable, and it is likely that there is more than one clone in cultivation. The appearance may also vary with age, soil, and general health of the tree. Many of the trees that have been referred to as 'non-descripts' in Bean's Manual, and on this website may be in fact poor specimens that could otherwise be included under this name.
The shape of the tree and the branching habit are not good, in fact it is often quite poor on older trees. The trunk sometimes does not produce the dappled bark for which planes are renowned. But the rich green glossy leaf is probably the best of any of the planes. Often the colour of the crown can clearly distinguish this form from others, which look yellowish by comparison. Despite the leaf colour, this is an inferior tree, especially in its shape in maturity. It should not be used for parkland planting, and nurseries should be encouraged to propagate from other varieties.
It is probably as widespread as it is because of its ease of propagation, and because it looks good when young. Extensive plantings can be seen in parkland. Some of the variation may be due to there being several similar clones in cultivation. The tree continues still to be widely planted, and many of the younger trees seen in London are of this or closely related varieties.
Bean makes specific mention of the trees in Green Park, which are mixed in avenues in the park with other London planes. It can be seen here that Pyramidalis makes a distinctly shorter tree than the other common forms, which are presumably of the same age and planting.
In the shape of the leaves and in the size and number of the fruits, this form is closer to Platanus occidentalis than are the other varieties seen in London.
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