Tree spotlight no:8 – Plane Tree

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2033 year old Plan Tree in Azerbaijan

Platanus is a genus consisting of a small number of tree species native to the Northern Hemisphere. They are the sole living members of the family Platanaceae. All members of Plantus 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 Ficus Sycomorus, the plant originally so named, and to the Sycamore maple Acer Pseudoplatanus.

london plane leaves and fruit.job

Botany:

The flowers are reduced and are borne in balls (globose heads); 3–7 hairy sepals may be fused at the base, and the petals are 3–7 and are spatulate. Male and female flowers are separate, but borne on the same plant (monoecious). The number of heads in one cluster (inflorescence) is indicative of the species (see table below). The male flower has 3–8 stamens; the female has a superior ovary with 3–7 carpels. Plane trees are wind-pollinated. Male flower-heads fall off after shedding their pollen.

After being pollinated, the female flowers become achenes that form an aggregate ball. Typically, the core of the ball is 1 cm in diameter and is covered with a net of mesh 1 mm, which can be peeled off. The ball is 2.5–4 cm in diameter and contains several hundred achenes, each of which has a single seed and is conical, with the point attached downward to the net at the surface of the ball. There is also a tuft of many thin stiff yellow-green bristle fibers attached to the base of each achene. These bristles help in wind dispersion of the fruits as in the dandelion.

plane tree seed head

The leaves are simple and alternate. The mature bark peels off or exfoliates easily in irregularly shaped patches, producing a mottled, scaly appearance. On old trunks, bark may not flake off, but thickens and cracks instead.

Uses

The principal use of these trees is as ornamental trees, especially in urban areas and by roadsides. The London plane is particularly popular for this purpose. The American plane is cultivated sometimes for timber and investigations have been made into its use as a biomass crop. The oriental plane is widely used as an ornamental and also has a number of minor medicinal uses.

Cultural history

Most significant aspects of cultural history apply to Platanus orientalis in the Old World. The tree is an important part of the literary scenery of Plato’s dialogue Phaedrus. Because of Plato, the tree also played an important role in the scenery of Cicero’s De Oratore.