The Platanus is both a genus and subgenus of trees. Characteristic of the genus are clusters of small flowers which give way to ball-shaped fruits that contain the tree's seeds. Mature bark cracks and flakes, giving the tree an irregular appearance. The genus includes the American sycamore, the London planetree, and less common varieties such as the Oaxaca plane, Kerr's plane, the Arizona sycamore, and the Chiapas plane.
Members of the Platanus genus are native to the Northern Hemisphere, and are known as sycamores or planetrees. Some, like the London planetree, have been spread throughout the world and well out of their native range. The Platanus members are hardy trees, they are largely disease and pest resistant, and when found in close proximity to each other, members have been known to cross-breed and create new species; this is how the London planetree was formed in a crossing between the American sycamore and the Oriental planetree. The fossil record suggests that these ancient trees have been in existence for about 115 million years, and representatives are still widespread.
The Rzedowski's plane, the Oaxaca plane, Gentry's plane, Chiapas plane, and the Mexican plane are all common sights around Mexico. The California sycamore is found throughout the western United States, while the Kerr's plane is common throughout Laos and Vietnam. Trees belonging to the Platanus genus are known as being well adapted to a number of different conditions and environments.
One of the largest and most distinctive of the Platanus trees in North America, the American sycamore, has long, alternating leaves, and mature trees develop gray, green, and white flaky bark characteristic of the genus. In the fall months, flowers give way to clusters of round fruits, which remain on the tree through the winter but make a mess when they drop. It is such a messy tree that it is best suited to parks and other large areas. Extremely tolerant of a variety of soils and able to withstand pollution and harsh urban conditions, it is also commonly used in cities and along streets.
The London planetree, a hybridized tree created from the American sycamore and the Oriental planetree, was first found in London in the 18th century. Not found growing in the wild, it is cultivated around the world. It has irregular white, gray, brown, and green bark similar to its American sycamore parent, though the fruits it develops form with only two on a single stalk. There have been several cultivars created to be more disease and pest resistant than the original, including the Bloodgood, the Liberty, and the Columbia. An extremely hardy tree, it can tolerate winter lows down to -40 °F (-37.3 °C).