Platanus
Encyclopedia
Platanus is a small genus of tree
s native to the Northern Hemisphere
. They are the sole living members of the family Platanaceae
.
They are all large trees to 30–50 m tall. All are deciduous
, except for P. kerrii, and are mostly 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 that term also refers to either the fig
Ficus sycomorus
, the plant originally so named, or the Great, or Sycamore Maple, Acer pseudoplatanus.
The flowers are reduced and are borne in balls (globose heads); 3–7 hairy sepal
s may be fused at the base, and the petals are 3–7 (or no) 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 stamen
s; 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 achene
s 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.
The leaves are simple
. In the subgenus Platanus they have a palmate outline. The base of the leaf stalk (petiole) is enlarged and completely wraps around the young stem bud in its axil. The axillary bud is exposed only after the leaf falls off.
The mature bark peels off (exfoliates) easily in irregularly shaped patches, producing a mottled, scaly appearance. On old trunks, bark may not flake off, but thickens and cracks instead.
There are two subgenera, subgenus Castaneophyllum containing the anomalous P. kerrii, and subgenus Platanus, with all the others; recent studies in Mexico have increased the number of accepted species in this subgenus. Within subgenus Platanus, genetic evidence suggests that P. racemosa is more closely related to P. orientalis than it is to the other North American species. There are fossil records of plane trees as early as 115 million years (the Lower Cretaceous). Despite the geographic separation between North America and Old World, species from these continents will cross readily resulting in fertile hybrids such as the London Plane.
disease
that can defoliate the trees in some years. The worst infections are associated with cold, wet spring weather. P. occidentalis and the other American species are the most susceptible, with P. orientalis the most resistant. The hybrid London Plane is intermediate in resistance.
Ceratocystis fimbriata f. platani, a wilt disease
, has become a significant problem in recent years in much of Europe.
Other diseases such as powdery mildew
occur frequently, but are of lesser importance.
Platanus species are used as food plants by the larva
e of some Lepidoptera
species including Phyllonorycter platani
and Setaceous Hebrew Character
.
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
has a number of minor medicinal uses.
in the Old World.
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s native to the Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
. They are the sole living members of the family Platanaceae
Platanaceae
Platanaceae is a family of flowering plants. It has been recognized by almost all taxonomists, and is sometimes called the "plane-tree family"....
.
They are all large trees to 30–50 m tall. All are deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
, except for P. kerrii, and are mostly found in riparian or other wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....
habitats
Habitat (ecology)
A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant or other type of organism...
in the wild, though proving drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
-tolerant in cultivation. The hybrid London Plane
London Plane
Platanus × acerifolia, the 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 and the Platanus occidentalis . Some authorities think that it may be a cultivar of P...
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 that term also refers to either the fig
Ficus
Ficus is a genus of about 850 species of woody trees, shrubs, vines, epiphytes, and hemiepiphyte in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extending into the semi-warm temperate zone. The Common Fig Ficus is a genus of...
Ficus sycomorus
Ficus sycomorus
Ficus sycomorus, called the sycamore fig or the fig-mulberry , sycamore, or sycomore, is a fig species that has been cultivated since ancient times...
, the plant originally so named, or the Great, or Sycamore Maple, Acer pseudoplatanus.
Botany
Sepal
A sepal is a part of the flower of angiosperms . Collectively the sepals form the calyx, which is the outermost whorl of parts that form a flower. Usually green, sepals have the typical function of protecting the petals when the flower is in bud...
s may be fused at the base, and the petals are 3–7 (or no) and are spatulate
Leaf shape
In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...
. Male and female flowers are separate, but borne on the same plant (monoecious). The number of heads in one cluster (inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
) is indicative of the species (see table below). The male flower has 3–8 stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...
s; 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 achene
Achene
An achene is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate and indehiscent...
s 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.
The leaves are simple
Leaf shape
In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...
. In the subgenus Platanus they have a palmate outline. The base of the leaf stalk (petiole) is enlarged and completely wraps around the young stem bud in its axil. The axillary bud is exposed only after the leaf falls off.
The mature bark peels off (exfoliates) easily in irregularly shaped patches, producing a mottled, scaly appearance. On old trunks, bark may not flake off, but thickens and cracks instead.
Phylogeny
Species
The following are recognized species of plane trees:| Scientific name | Common name | Distribution | flowerheads | Notes |
|---|---|---|---|---|
| Platanus × acerifolia (P. occidentalis × P. orientalis; syn. P. × hispanica, P. × hybrida) |
London Plane, Hybrid Plane | Cultivated origin | 1–6 | Subgenus Platanus |
| Platanus chiapensis | Chiapas Plane | southeast Mexico Mexico The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of... |
? | Subgenus Platanus |
| Platanus gentryi | Gentry's Plane | western Mexico Mexico The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of... |
? | Subgenus Platanus |
| Platanus kerrii | Kerr's Plane | Laos Laos Laos Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ Sathalanalat Paxathipatai Paxaxon Lao, officially the Lao People's Democratic Republic, is a landlocked country in Southeast Asia, bordered by Burma and China to the northwest, Vietnam to the east, Cambodia to the south and Thailand to the west... , Vietnam Vietnam Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –... |
10–12 | Subgenus Castaneophyllum |
| Platanus mexicana | Mexican Plane | northeast and central Mexico Mexico The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of... |
2–4 | Subgenus Platanus |
| Platanus oaxacana | Oaxaca Plane | southern Mexico Mexico The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of... |
? | Subgenus Platanus |
| Platanus occidentalis | American Sycamore, American Plane, Buttonwood, Occidental Plane | eastern North America North America North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas... |
1–2 | Subgenus Platanus |
| Platanus orientalis Platanus orientalis Platanus orientalis, or the Oriental plane, is a large, deciduous tree of the Platanaceae family, known for its longevity and spreading crown. The species name derives from its historical distribution eastward from the Balkans, where it was recognized in ancient Greek history and literature.... |
Oriental Plane | southeast Europe Europe Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting... , southwest Asia Asia Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population... |
3–6 | Subgenus Platanus |
| Platanus racemosa | California Sycamore, Western Sycamore, Aliso | California California California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area... |
3–7 | Subgenus Platanus |
| Platanus rzedowskii | Rzedowski's Plane | eastern Mexico Mexico The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of... |
? | Subgenus Platanus |
| Platanus wrightii Platanus wrightii Platanus wrightii , is a sycamore tree native to Arizona and New Mexico with its range extending south into Sonora, and a small area of Chihuahua Mexico.... |
Arizona Sycamore | Arizona Arizona Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix... , New Mexico New Mexico New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S... , northwest Mexico Mexico The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of... |
2–4 | Subgenus Platanus |
Diseases
Planes are susceptible to Plane Anthracnose (Apiognomonia veneta), a fungalFungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
that can defoliate the trees in some years. The worst infections are associated with cold, wet spring weather. P. occidentalis and the other American species are the most susceptible, with P. orientalis the most resistant. The hybrid London Plane is intermediate in resistance.
Ceratocystis fimbriata f. platani, a wilt disease
Wilt disease
A wilt disease is any number of diseases that affect the vascular system of plants. Attacks by fungi, bacteria, and nematodes can cause rapid killing of plants, large tree branches or even entire trees....
, has become a significant problem in recent years in much of Europe.
Other diseases such as powdery mildew
Powdery mildew
Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of fungi in the order Erysiphales. It is one of the easier diseases to spot, as its symptoms are quite distinctive. Infected plants display white powdery spots on the...
occur frequently, but are of lesser importance.
Platanus species are used as food plants by the larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e of some Lepidoptera
Lepidoptera
Lepidoptera is a large order of insects that includes moths and butterflies . It is one of the most widespread and widely recognizable insect orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...
species including Phyllonorycter platani
Phyllonorycter platani
Phyllonorycter platani is a moth of the family Gracillariidae. It is found in Europe, the Near East and the eastern Palearctic ecozone, as well as California.The wingspan is 8-10 mm. The moth flies in two generations from mid June to November. ....
and Setaceous Hebrew Character
Setaceous Hebrew Character
The Setaceous Hebrew Character is a moth of the family Noctuidae. It is found in the Palearctic ecozone. It is a common species throughout Europe. It is also found in North America, from coast to coast across Canada and the northern United States to western Alaska. It occurs in the Rocky Mountains...
.
Uses
The principal use of these trees is as ornamental trees, especially in urban areas and by roadsides. The London planeLondon Plane
Platanus × acerifolia, the 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 and the Platanus occidentalis . Some authorities think that it may be a cultivar of P...
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
Biomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....
crop. The oriental plane
Oriental Plane
Platanus orientalis, or the Oriental plane, is a large, deciduous tree of the Platanaceae family, known for its longevity and spreading crown. The species name derives from its historical distribution eastward from the Balkans, where it was recognized in ancient Greek history and literature....
has a number of minor medicinal uses.
Cultural history
Most significant aspects of cultural history apply to Platanus orientalisPlatanus orientalis
Platanus orientalis, or the Oriental plane, is a large, deciduous tree of the Platanaceae family, known for its longevity and spreading crown. The species name derives from its historical distribution eastward from the Balkans, where it was recognized in ancient Greek history and literature....
in the Old World.
External links
- Botany of Plane trees
- Flora of North America: Platanus
- A collection of images, including detailed photographs of fruit and flowers, from GERM.
- A short informal account concentrating on the North American species
- A developmental and evolutionary analysis of embryology in Platanus (platanaceae), abasal eudicot, abstract of article by Sandra K. Floyd et al. in American Journal of Botany, 1999;86:1523-1537.