Platanus occidentalis, also known as American sycamore, American planetree, western plane, occidental plane, buttonwood, and water beech, is a species of Platanus native to the eastern and central United States, the mountains of northeastern Mexico, extreme southern Ontario, and extreme southern Quebec. It is usually called sycamore in North America, a name which can refer to other types of trees in other parts of the world; in the United Kingdom, for example, the name sycamore typically refers to Acer pseudoplatanus. The American sycamore is a long-lived species, typically surviving at least 200 years and likely as long as 500–600 years. It is capable of becoming a massive tree, with a wide girth and heights reaching up to or more.

The species epithet occidentalis is Latin for "western", referring to the Western Hemisphere, because at the time when it was named by Carl Linnaeus, the only other species in the genus was P. orientalis ("eastern"), native to the Eastern Hemisphere. Confusingly, in the United States, this species was first known in the Eastern United States, thus it is sometimes called eastern sycamore, to distinguish it from Platanus racemosa, which was discovered later in the Western United States and called western sycamore.

Description

Platanus occidentalis can often be easily distinguished from other trees by its mottled bark that flakes off in large, irregular masses, leaving the surface mottled and gray, greenish-white, and brown. The bark of all trees has to yield to a growing trunk by stretching, splitting, or infilling, but sycamore bark is more rigid and less elastic than the bark of other trees, so to accommodate the growth of the wood underneath, the tree sheds it in large, brittle pieces.

A sycamore can grow to massive proportions, typically reaching up to high and in diameter when grown in deep soils. The largest of the species have been measured to , and nearly in diameter. Larger specimens were recorded in historical times. In 1744, a Shenandoah Valley settler named Joseph Hampton and two sons lived for most of the year in a hollow sycamore in what is now Clarke County, Virginia. In 1770, at Point Pleasant, Virginia (now in West Virginia), near the junction of the Kanawha and Ohio Rivers, George Washington recorded in his journal a sycamore measuring in circumference at from the ground.

The sycamore tree is often divided near the ground into several secondary trunks, very free from branches. Spreading limbs at the top make an irregular, open head. Roots are fibrous. The trunks of large trees are often hollow.

Another peculiarity is the way the leaves grow sticky, green buds. In early August, most trees have tiny buds nestled in the axils of their leaves, which produce the leaves of the coming year. The sycamore branch apparently has no such buds. Instead, an enlargement of the petiole encloses the bud in a tight-fitting case at the base of the petiole. It can be found in southeastern Minnesota. and it is sold as far south as Okeechobee. The American sycamore is also well adapted to life in Argentina and Australia and is quite widespread across the Australian continent, especially in the cooler southern states such as Victoria and New South Wales.

Ecology

American sycamore is found most commonly in bottomland or floodplain areas, thriving in the wet environments provided by rivers, streams, or abundant groundwater, though it will die after being flooded for more than two weeks at a time. It is a fast-growing, early-mid successional hardwood tree species. Its life cycle follows the pattern of a "weedy" species: it grows mature enough to reproduce rather young and produces large numbers of wind-distributed seeds. The dominance of sycamore in a forest depends on the conditions where it grows; it is often a pioneer species, but in the wet sites that are most ideal for it, it persists as a subclimax to climax species, partly because of its fast growth and very long lifespan. The heartwood of a sycamore tree decays quickly, producing large hollow cavities in the center of the trees which are used by many animals as nesting sites.

Uses

thumbnail|Wood of P. occidentalis from [[Romeyn Beck Hough's 14-volume work The American Woods, a collection of over 1000 paper-thin wood samples representing more than 350 varieties of North American trees]]

The American sycamore is able to endure a big-city environment and was formerly extensively planted as a shade tree,

Its wood has been used extensively for butcher's blocks. It has been used for boxes and crates; although coarse-grained and difficult to work, it has also been used to make furniture, siding, and musical instruments.

Use by Native Americans

The tree bark has traditionally been used by Native Americans to make little dishes for gathering whortleberries.

Pests and diseases

The American sycamore is a favored food plant of the pest sycamore leaf beetle.

thumb|left|upright|Severe infections of anthracnose can sometimes defoliate large swaths of sycamore during mid- and late spring, but trees generally recover by mid-summer

American sycamore is susceptible to plane anthracnose disease (Apiognomonia veneta, syn. Gnomonia platani), an introduced fungus found naturally on the Oriental plane P. orientalis, which has evolved considerable resistance to the disease. Although rarely killed or even seriously harmed, American sycamore is commonly partially defoliated by the disease, rendering it unsightly as a specimen tree.

Sometimes mistaken for frost damage, the disease manifests in early spring, wilting new leaves and causing mature leaves to turn brown along the veins. Infected leaves typically shrivel and fall, so that by summer, the tree is regrowing its foliage. Cankers form on twigs and branches near infected leaves, serving to spread the disease by spore production and also weakening the tree. Because cankers restrict the flow of nutrients, twigs and branches afflicted by cankers eventually die. Witch's broom is a symptom reflecting the cycle of twigs dying.

As a result of the fungus' damage, American sycamore is often avoided as a landscape tree, and the more resistant London plane (P. × hispanica; hybrid P. occidentalis × P. orientalis) is planted, instead.

History

The terms under which the New York Stock Exchange was formed are called the "Buttonwood Agreement", because it was signed under a buttonwood (sycamore) tree at 68 Wall Street, New York City in 1792.

The sycamore made up a large part of the forests of Greenland and Arctic America during the Cretaceous and Tertiary periods. It once grew abundantly in central Europe, from which it has now disappeared.

See also

  • Buttonball Tree, an American sycamore, said to be the largest on the East Coast, located in Sunderland, Massachusetts
  • Pinchot Sycamore, an American sycamore that is the largest tree in Connecticut
  • Webster Sycamore, formerly the largest American sycamore in West Virginia
  • Sycamore maple or European sycamore (Acer pseudoplatanus), a maple which is visually very similar to sycamore

References

Further reading

  • University of Michigan at Dearborn: Native American Ethnobotany of Platanus occidentalis (American sycamore)
  • Cirrusimage.com: American Sycamore — diagnostic photographs and information
  • Forestry.about.com: American sycamore - Platanus occidentalis
  • Bioimages.vanderbilt.edu: photos of Platanus occidentalis