London plane tree leaf

Platanus x acerifolia ‘Liberty’: ‘Liberty’ London Planetree1

Edward F. Gilman and Dennis G. Watson2

Introduction

This is a large tree resulting in a cross between Platanus orientalis and Platanus occidentalis suitable for use in USDA hardiness zone 4b or warmer. It is reportedly more resistant to powdery mildew and anthracnose, though not immune. The tree will reach a height of 85 feet and a spread of 70 feet. Pyramidal in youth, it develops a spreading rounded crown with age supported by a few, very large-diameter branches. These branches should be spaced two to four feet apart along the trunk to develop a strong structure. The dominant central leader which typically develops on London Planetree usually assures that the structure of major limbs is desirable with little corrective pruning required other than removing occasionally occurring upright branches with tight crotches. It is also helpful to thin out the many branches which develop early on the central trunk. The bark is patchy and very attractive and may be the plants best ornamental attribute. These patches range from creamy-white to olive-green. Large sections of bark may be shed from the tree as it grows older. This is normal and only needs to be disposed of. It does not indicate a problem with the tree.

Figure 1.

Middle-aged Platanus x acerifolia ‘Liberty’: ‘Liberty’ London Planetree

Credit:

Ed Gilman

General Information

Scientific name: Platanus x acerifolia Pronunciation: PLAT-uh-nus x ass-er-ih-FOLE-ee-uh Common name(s): ‘Liberty’ London Planetree Family: Platanaceae USDA hardiness zones: 5A through 9A (Fig. 2) Origin: not native to North America Invasive potential: little invasive potential Uses: specimen; street without sidewalk; shade; parking lot island > 200 sq ft; sidewalk cutout (tree pit); tree lawn > 6 ft wide; urban tolerant; highway median Availability: not native to North America Figure 2.

Range

Description

Height: 70 to 85 feet Spread: 50 to 70 feet Crown uniformity: symmetrical Crown shape: pyramidal, round, spreading Crown density: dense Growth rate: fast Texture: coarse

Foliage

Leaf arrangement: alternate (Fig. 3) Leaf type: simple Leaf margin: lobed, incised Leaf shape: ovate, star-shaped Leaf venation: palmate, pinnate Leaf type and persistence: deciduous Leaf blade length: 4 to 8 inches, 8 to 12 inches Leaf color: green Fall color: yellow Fall characteristic: not showy Figure 3.

Foliage

Flower

Flower color: red Flower characteristics: not showy

Fruit

Fruit shape: round Fruit length: .5 to 1 inch Fruit covering: dry or hard Fruit color: brown Fruit characteristics: does not attract wildlife; showy; fruit/leaves a litter problem

Trunk and Branches

Trunk/bark/branches: branches droop; showy; typically one trunk; thorns Pruning requirement: little required Breakage: resistant Current year twig color: brown Current year twig thickness: medium Wood specific gravity: unknown

Culture

Light requirement: full sun Soil tolerances: clay; sand; loam; alkaline; acidic; extended flooding; well-drained Drought tolerance: high Aerosol salt tolerance: moderate

Other

Roots: can form large surface roots Winter interest: yes Outstanding tree: yes Ozone sensitivity: unknown Verticillium wilt susceptibility: resistant Pest resistance: sensitive to pests/diseases

Use and Management

The plant tolerates dry soil (but scorches in dry weather) and city conditions well, adapts to most soils including alkaline and is more resistant (not immune) to the anthracnose that afflicts Platanus occidentalis . However, it is susceptible to canker stain, a disease which has caused its demise in some areas, and is often seen infested with lace bugs which will not kill the tree but causes premature defoliation in late summer. It is also reported to be susceptible to ozone pollution injury in laboratory tests at levels often present during the summer, but damage from air pollution in the landscapes appears minimal. Some people object to the large leaves which often begin falling from the tree in late summer.

Some horticulturists consider this a messy tree due to early leaf drop from drought, bark shedding, and lace bugs. Leaves blow around in the wind during the fall and decompose slowly in the landscape creating a distinctive “crunch” underfoot. Lea, but they make great compost in a compost pile.

Some tree managers limit its use as a street tree due to its large size, susceptibility to canker stain, bacterial leaf scorch, and lace bug injury. But it is a good durable tree for many areas where soil is poor and compacted. It is also somewhat tolerant of coastal conditions, and well-adapted to areas with poor drainage. But it may be best saved for moist sites with plenty of room for root and crown expansion. `Liberty’ is more susceptible to anthracnose than `Bloodgood’ and is somewhat difficult to propagate. `Columbia’ is less hardy than `Bloodgood’ and easier to propagate than `Liberty’.

The National Arboretum released in 1984 another Platanus occidentalis x Platanus orientalis which could prove to be superior to the parents: Platanus x acerifolia `Columbia’ – upright, orange-grey bark, five-lobed leaves.

Propagation is by seed or hardwood cuttings.

Pests

Both aphids and lace bugs can infest this tree. Neither, however, will kill it. Aphids will suck the sap from Planetree. Heavy infestations deposit honeydew on lower leaves and objects beneath the tree, such as cars and sidewalks.

Sycamore lace bugs feed on the undersides of the leaves causing a stippled appearance, bronze leaves in summer and premature defoliation in late summer. The insects leave black flecks on the lower leaf surface.

Diseases

Anthracnose: `Bloodgood’ has been shown to be resistant to anthracnose, but it is not immune. `Liberty’ is more susceptible than `Bloodgood’. Anthracnose causes early symptoms on young leaves resembling frost injury. When the leaves are almost fully grown light brown areas appear along the veins. Later the infected leaves fall off and trees may be nearly completely defoliated in spring or early summer. The disease can cause twig and branch cankers and a witches-broom appearance at the end of the branches. The trees send out a second crop of leaves but repeated attacks can lower tree vigor. Use a properly labeled fungicide to help control the disease. Fertilization helps trees withstand repeated defoliation.

Canker stain is very serious on London Planetree and can kill the tree, bacterial leaf scorch can devastate London Planetree and some fungi cause leaf spots.

Footnotes

This document is ENH647, one of a series of the Environmental Horticulture, UF/IFAS Extension. Original publication date November 1993. Revised December 2006. Reviewed February 2014. Visit the EDIS website at http://edis.ifas.ufl.edu.

Edward F. Gilman, professor, Environmental Horticulture Department; Dennis G. Watson, former associate professor, Agricultural Engineering Department, UF/IFAS Extension, Gainesville, FL 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county’s UF/IFAS Extension office.
U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.

London Planetree

Bark of London Planetree
G. Lumis

Leaf of London Planetree
G. Lumis

London Planetree
G. Lumis

Scientific Name: Platanus acerifolia

Summary
Foliage: Deciduous broadleaf
Height: 75 to 100 feet
Spread: 65 to 80 feet
Shape: Spreading

Large green leaves have no effective fall color. The ornamental bark flakes off, exposing white, smooth bark underneath.

Plant Needs
Zone: 5 to 8
Light: Partial shade to full sun
Moisture: Wet to moist
Soil Type: Sandy, loam, or clay
pH Range: 3.7 to 6.5

Functions
Suggested uses for this plant include shade and specimen plant.

Planting Notes
Transplants readily. Tolerates wide range of conditions, including air pollution. Plant in a location that will allow the plant ample room to spread. Do not plant where branches will interfere with power lines.

Care
Bark and leaves continuously drop off, causing litter. Tolerates heavy pruning. Prune in the winter.

Problems
Some problems include cankerstain, anthracnose, lacebug, and frost cracking of the bark.
London Planetree is a better choice than the native American Sycamore (PLATANUS OCCIDENTALIS) because of its resistant to anthracnose.

Alternatives
Consult local sources, including historic or public gardens and arboreta, regarding cultivars and related species that grow well in your area.

Cultivars of PLATANUS X ACERIFOLIA
`Bloodgood’ is faster growing and more resistant to anthracnose than the species.

The most striking feature of the London Planetree is its flaking bark that peels to reveal a lighter colored bark underneath. Best used only in open areas where its growth will not be restricted.

London planetree

Tree & Plant Care

Plants grow best in moist, deep, rich well-drained soil in full sun. Does not tolerate shady sites.
Soil pH adaptable, moderately salt and drought tolerant.
Can be a messy tree since drops a lot of leaves, twigs and fruit.

Disease, pests, and problems

Can be affected by canker stain, anthracnose, leafspots, aphids, plant bug, scales, and borers.
Young plants can be susceptible to frost cracks.

Disease, pest, and problem resistance

Some cultivars vary in their resistance to anthracnose (see cultivars below).
Tolerant of high pH soil.

Native geographic location and habitat

Of hybrid origin.

Bark color and texture

Unique, gray-brown flaky scales that shed to expose mottled peeling patches of white, gray, and green. Trees become nearly white near the top of tree.

Leaf or needle arrangement, size, shape, and texture

Simple, alternate, 6 to 7 inch wide leathery leaves have 3 to 5 lobes, similar to maple.
The leaf surface is bright green and paler underneath; margins are untoothed or nearly so.
Fall color is yellow-brown.

Flower arrangement, shape, and size

Monoecious, with separate male and female flowers. Flowers appear in early spring with the leaves as dense globose balls on long stalks (peduncles).
Male flowers are green , females are showier, bright burgundy-red.
Not ornamentally important

Fruit, cone, nut, and seed descriptions

Ball-like seed heads (1 inch diameter) hang in pairs from long stalks. Seeds shatter during winter months.

Cultivars and their differences

‘Bloodgood’ (Platanus x acerifolia ‘Bloodgood’): Shows some resistance to anthracnose.

Exclamation!™ (Platanus x acerifolia ‘Morton Circle’): This cultivar is resistant to anthracnose and frost cracking. The habit is more uniform and upright than the species. Grows 60 feet high and 30 feet wide. Introduced by Chicagoland Grows®, Inc.

Ovation™ (Platanus x acerifolia ‘Morton Euclid’): This cultivar is also resistant to anthracnose and frost cracking. The habit is rounded to broadly pyramidal. Grows 60 feet high by 50 feet wide. Introduced by Chicagoland Grows®, Inc.

Landscape Plants

  • Broadleaf deciduous tree, 70-100 ft (21-30 m), open, spreading with age. Bark exfoliates and is cream, olive, light brown, best asset of the tree. Leaves alternate, simple, 3-5 lobed, 15-18 cm x 20-25 cm, triangular-ovate or broad triangular, margins may be toothed to entire. Flowers appear in spring, in dense globose clusters, monoecious, and male (yellowish) and female (reddish) clusters are somewhat similar in appearance. Fruit is a small achene, many densely packed into globose clusters about 2.5 cm in diameter, they remain on the tree long after leaves have fallen.
  • Sun or light shade. Prefers deep, rich, moist, well-drained soil, but will grow in about anything. Withstands high pH, and pollution, and grime of cities. Susceptible to anthrachnose and powdery mildew, which may disfigure the leaves in early summer. Widely planted in London. It withstands heavy pruning and is frequently pollarded.
  • Hardy to USDA Zone 4 Found growing in London in 1663, a cross between Platanus orientalis (Oriental Planetree) and Platanus occidentalis (American Sycamore). Platanus orientalis can be very difficult to distinguish from its American parent. Distinguishing features include: P. × acerifolia leaves have deeper sinuses, lobes of leaves are about as long as wide (P. occidentalis lobes wider than long), and fruit clusters are mostly in pairs (P. occidentalis clusters mostly solitary).
  • Often listed as Platanus × acerifolia in accordance with its hybird nature. However, the ITIS now listes the accepted name as Platanus acerifolia.
  • Several selections available, including:
    • ‘Bloodgood’- an old and popular cultivar that has a reputation for having anthracnose resistance. This selection is somehow linked to the James Bloodgood & Co. Nursery of Long Island, New York, which ceased business in 1919. The tree apparently was being propagated from cuttings long before it was named in 1900 by the Meehan nursery in Pennsylvania (Jacobson, 1996).
    • Exclamation™ (‘Morton Circle’) – a more recent selection that was developed at the Morton Arboretum, Lisle, IL. It is reported to be resistant to anthracnose and moderately resistant to powdery mildew. The original plant has been under observation since 1994.
  • Platanus: the Greek name for P. orientalis. acerifolia: leaves like those of Acer (maple).

  • Oregon State Univ. campus: many on Jefferson Ave., east of 15th St.

Plane tree

Plane tree, any of the 10 species of the genus Platanus, the only genus of the family Platanaceae. These large trees are native in North America, eastern Europe, and Asia and are characterized by scaling bark; large, deciduous, usually palmately lobed leaves; and globose heads of flower and seed. The plane trees bear flowers of both sexes on the same tree but in different clusters. The sycamore maple (Acer pseudoplatanus), often called sycamore, plane, or mock plane, is distinct (see maple).

Leaves and seedballs of the Oriental plane tree (Platanus orientalis)A to Z Botanical Collection/Encyclopædia Britannica, Inc.

The American plane tree, or sycamore (P. occidentalis), also known as buttonwood, buttonball, or whitewood, is the tallest, sometimes reaching a height of more than 50 m (160 feet). Its pendent, smooth, ball-shaped seed clusters usually dangle singly and often persist after leaf fall. Native from southeastern Europe to India, the Oriental plane (P. orientalis) reaches 30 m (100 feet) with huge, often squat boles—some measuring nearly 10 m in circumference (about 10 feet in diameter). Its bristly seedballs hang in clusters of two to six. The London plane (P. acerifolia), a hybrid between the American and the Oriental planes, combines characteristics of both in varying degrees. It is a little shorter and more squat than the American tree and usually has bristly, paired seedballs. There are variegated forms of London plane. The California sycamore (P. racemosa), about 25 m (80 feet) tall, has contorted branches, thick leaves, and bristly seedballs in groups of two to seven.

The London plane is planted widely in cities for its resistance to air pollution and to diseases that more readily affect other plane trees. All planes grow rapidly and furnish quick shade. Many are picturesque in winter for their patchy bark: as the outer bark flakes off, inner bark shows up in shades of white, gray, green, and yellow.

London Planetree: A Tough Dweller with a Confusing Past

“Anyone who measures the height of two London planes at Bryanston, Dorset, will assume either he, or his hypsometer (a measuring device), has gone barmy,” writes Thomas Parkenham in his book, Meeting with Remarkable Trees.

Parkenham’s humorous enthusiasm is directed at two magnificent London planetrees “girthing” at 16 and 18 feet. He says that their massive trunks give them “such graceful proportions that they rise effortlessly from the ferny track, as though there was nothing in this achievement and British woods were stuffed…full of trees 160 feet high.” Instead, they are Britain’s two tallest hardwoods.

Not only do the London planes, as they are sometimes called, tower over the beeches, oaks, lindens, and ash that make up their neighbors, they have the distinct advantage of being able to withstand air pollution and other stresses of urban life better than their native associates. It is the quality that has made the London plane as popular with U.S. city foresters as it is with tree lovers in England.

London planetrees are not a species, but rather the result of a cross between two species from widely divergent parts of the globe. The parents are both the Platanaceae family, a far-flung group with one species native to Southeast Europe through northern Persia, one in Indochina, seven found in southwest North America and Mexico, and our common sycamore of eastern United States. The two that were (and still are) crossed to produce London planetrees are our very own American sycamore (Platanus occidentalis) of southeast Europe and the eastern Mediterranean region.

How this happy combination took place, unfortunately, is lost to time. One popular story is that the union occurred in John Tradescant’s garden. He was the gardener for Charles I and is known to have visited eastern America three times in the mid-17th century. Others doubt that his transplants would have been large enough to bear flowers and have seeds. The doubters claim that the hybrid was created in Spain. In fact, this tree is sometimes referred to by a name suggesting that region — Platanus x hispanica. Regardless of its origin, the new offspring of the cross was discovered to tolerate the nastiest of smoke and grime in London. Because of this, its fame spread and for 300 years it has been produced by nurseries that supply trees to cities throughout the moderate climate regions of the world.

What’s in a Name?

London is where the city-tolerant features of London planetree were discovered, but where does the “plane” come from? There is some argument among authorities about the intended meaning, but the word itself is from the scientific name of the genus, Platanus, which comes from the Greek word platys. This apparently means “ample,” but whether it referred to the spreading branches and shady foliage of this tree or its large, broad leaves, no one is sure.

Whatever the meaning, London planetree is sometimes erroneously referred to as sycamore (a name better applied to one of its parents, American sycamore) or simply plane tree.

In the Landscape
The London planetree is a widely planted street tree, and for good reason. The tree was found to thrive in sooty air and provide wonderful shade. Its ability to withstand air pollution, drought, and other adversities assures its popularity as an urban tree (hardiness zones 5-9). Strong limbs also help make the London planetree a good choice where site conditions allow for its large size.

Beyond its reputation as a survivor, this tree is simply worth admiring. The unique bark and interesting branching give it amazing visual appeal. It’s towering height (75-100 feet) makes it ideal for shade and cutting energy costs.

Read Norway Spruce: Loftiest on the Continent.

London Plane Tree

London Plane Tree – Platanus x acerifolia
The most striking feature of the London Plane Tree is its flaking bark that peels to reveal a lighter colored bark underneath. It might also be called the tree with the camouflage or jigsaw puzzle bark. A member of the sycamore family, the first record of the tree was in 1663 when the hybrid of the American and oriental Plane tree was found growing in London, where it is the dominant street tree. It also comprises 4% of New York City trees, but 14% of the city’s total leaf area and it gives a lot prettier, shady, air-filtering, evaporative-cooling leaves per single trunk than most of the other species in a city. London plane trees are the best trees in New York City for carbon storage and sequestration.
The leaves are coarse and resemble maple leaves in shape and have 3 to 5 sharply pointed lobes and may measure up to 6 or 8 inches long and 8 or 10 inches across. They have smooth, dull medium green surfaces and paler undersides with hairy veins. They emerge in late spring, most dropping in December. The flowers emerge in late May or early June about the same time that the leaves show. They are formed in round clusters about 1 inch in diameter. A yellowish green, both male and female are inconspicuous. These clusters develop over the season into seed balls that are brown and fuzzy. About 1 to 1 1/2-inches around, they are green at first, turning brown as the seeds within mature. These balls hang on the tree, two or three to a stalk, through the fall and much of the winter before beginning to shed the seeds in the spring. They are not attractive to wildlife. The tree can also be pollarded and pleached to form lovely hedges and allees.

Platanus acerifolia – maple-leaved sycamore

The maple-leaved sycamore or ordinary sycamore belongs to the family of the sycamore family and was created in the mid-17th century by the crossing of Oriental sycamore and American sycamore. The maple-leaved shape of the plane tree is extremely robust and is a popular street tree tolerating exhaust and polluted air in many countries.

Habit

The maple-leaved plane tree is of broad-crowned growth and can grow up to 40 meters in height. Strong branches are formed on the relatively short trunk. The bark is yellow to gray-brown and dissolves into plates annually, which causes the characteristic pattern of trunk and branches. The leaves are arranged alternately and divided into leaf blade and petiole. The petiole can grow to ten centimeters long.

Buds

The winter buds of the maple-leaved sycamore can only be seen after the leaf fall. The ten-millimeter-sized buds surround an annular leaf scar. The reddish-brown buds are very large and have a slightly bent tip.

Blossom

The maple-leaved sycamore is a monoecious, single-sexed plant. The flowers appear together with the foliage, about the beginning of May. Most of the flowers are in pairs on the kitty. While the male flowers are quite small and appear greenish-yellow, the crimson female flowers are more eye-catching.

Fruits

The fruit is spherical and hangs on a long stem. The single fruits are cylindrically shaped and edged nutlets containing the seed. In about September or October, the fruit ripeness takes place. However, the fruits of the maple-leaved sycamore are so-called winter-eaters. This means that the fruits remain on the tree until next spring. Then, when their decay begins, the tiny hair surrounding the individual fruits can cause coughing in humans.

The wood of the maple-leaved plane tree

The maple-leaved sycamore has a light sapwood and a reddish heartwood. The wood can be worked very well and is preferably used as veneer or wood turner. Mainly the wood is used in interior design, but is also used as firewood in use. Due to the low stamina, cracks in the drying of planewood can easily occur. While the wood can be well polished and matted, it is hardly weatherproof and therefore less durable.

The Secret History Of The London Plane Tree

Photo: Tubb.

The London plane tree accounts for over half of our city’s tree population. With such arboreal omnipresence it’s easy to overlook just what a distinctive tree this is. The sight that catches at eye level and will be familiar to most people is its khaki camouflage-patterned bark. This mottled mix of grey, olive and cream is pleasing on the eye and if you could imagine such a thing as a benign militia lining our city streets, it would surely look something like a procession of London planes.

Yet despite the tree’s ubiquity it was only ‘discovered’ in the mid-17th century by John Tradescant the younger in his famous nursery garden and ark in Vauxhall. And ‘discovered’ in the sense that there’s a possibility the tree did not exist before this time.

So why was London’s most popular tree so late on the scene?

London plane’s famous bark: Photo: Tributory.

Here we have to go into the tree’s family history. The London Plane is most likely a hybrid between the American sycamore and the majestic Oriental plane. It took a long time for these ‘lovers’ to meet — the two trees thwarted by growing on opposite sides of the globe. But it seems the voyages of the early modern period with routine collections of specimens being brought home led to the American sycamore’s journey from its native eastern America, and the Oriental plane from southeast Europe. The first account of the Oriental plane in Britain is found in William Turner’s 1548 book: Names Of Herbs. While the American sycamore perhaps arrived some 150 years or so later at the beginning of the 17th century.

Due to the height of the trees it is possible to peer into Berkeley Square from a distance. Photo: Anatoleya.

The London plane would then have hybridised when its ‘parents’ found themselves sharing the same space. There is some probability that this was in the very Vauxhall garden where Tradescant first found the tree since both requisite family members were indeed there.

But how did it go from interesting curiosity to the urban tree of choice lining so many of London’s streets? It was planted en masse at a time when London was black with soot and smoke from the Industrial Revolution and when population expansion forced greater urban planning. Taking a cue from the plane-lined boulevards built in Paris from around 1850, the tree flourished in London due to its hardy characteristics.

Pollarded planes in John Islip Street. Photo: Jim Linwood.

Take that camouflage bark, for instance, it’s more than just an accidentally attractive quality. It has that pattern because the bark breaks away in large flakes in order that the tree can cleanse itself of pollutants. It also requires little root space and can survive in most soils. True, it grows to some 30 metres tall so when trees line a street they can cause problems for London buses and overhanging wires. But then it’s also an unusual tree in that it can flourish despite pollarding (the pruning of branches that often gives the tree a club-limbed appearance). The rather beautiful maple-like leaves, shaped like a five pointed star, also have an otter-like sleekness. The daily London grime simply rinses away, leaving the leaves a lush green.

The plane’s canopy of leaves. Photo: Andrea Kirkby.

However, the plane does maintain many of its ornamental qualities too. The best place to view the tree is perhaps Berkeley Square. Here the 30 or so examples were planted in 1789 and are among the oldest in London. What’s more, due to the height by which the branches expand into a canopy like structure, Berkeley Square is one of only a few where it’s possible to peer into the square from a distance (usually while attempting to cross the Mayfair streets).

Photo: Nigel Bewley.

The one real negative quality is for allergy sufferers, who must be wary of the spores released from the tree’s fruit. But those that don’t have this to consider will find these comical little baubles another pleasing quality.

All in all it is a tree that can be said to be a true Londoner born and bred, to the extent that it even took the city’s name.

For more on the London plane try The Great Trees Of London (Time Out) and The Trees That Made Britain by Archie Mills.

Leave a Reply

Your email address will not be published. Required fields are marked *