| American sycamore | |
|---|---|
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| A25 ft 8 in (8 m) girth tree inSunderland, Massachusetts | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Order: | Proteales |
| Family: | Platanaceae |
| Genus: | Platanus |
| Species: | P. occidentalis |
| Binomial name | |
| Platanus occidentalis | |
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| Generalized natural range ofPlatanus occidentalis | |
Platanus occidentalis, also known asAmerican sycamore,American planetree, western plane,[3]occidental plane, buttonwood, and water beech,[4] is a species ofPlatanus native to the eastern and central United States, the mountains of northeastern Mexico, extreme southernOntario,[5][6] and extreme southernQuebec.[7] It is usually calledsycamore 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 toAcer pseudoplatanus. The American sycamore is a long-lived species, typically surviving at least 200 years and likely as long as 500–600 years.[8] It is capable of becoming a massive tree, with a wide girth and heights reaching up to 24 m (80 ft) or more.[9]
The species epithetoccidentalis is Latin for "western", referring to theWestern Hemisphere, because at the time when it was named byCarl Linnaeus, the only other species in the genus wasP. orientalis ("eastern"), native to theEastern Hemisphere. Confusingly, in the United States, this species was first known in theEastern United States, thus it is sometimes called eastern sycamore,[10][11] to distinguish it fromPlatanus racemosa which was discovered later in theWestern United States and called western sycamore.
Platanus occidentalis can often be easily distinguished from other trees by its mottled bark which 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.[12]
A sycamore can grow to massive proportions, typically reaching up to 30 to 40 m (98 to 131 ft) high and 1.5 to 2 m (4.9 to 6.6 ft) in diameter when grown in deep soils. The largest of the species have been measured to 53 m (174 ft), and nearly 4 m (13 ft) 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.[13] In 1770, atPoint Pleasant, Virginia (now inWest Virginia),[14] near the junction of theKanawha andOhio Rivers,George Washington recorded in his journal a sycamore measuring 13.67 m (44 ft 10 in) in circumference at 91 cm (3 ft) from the ground.[15]
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 will have tiny buds nestled in theaxils of their leaves which will produce the leaves of the coming year. The sycamore branch apparently has no such buds. Instead there is an enlargement of thepetiole which encloses the bud in a tight-fitting case at the base of the petiole.[12]
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In its native range, it is often found inriparian andwetland areas. The range extends fromIowa toOntario andNew Hampshire in the north,Nebraska in the west, and south toTexas andFlorida. It is apparentlyextirpated fromMaine.[16] It can be found in southeasternMinnesota.[17][18][16] Closely related species (seePlatanus) occur in Mexico and the southwestern states of the United States. It is sometimes grown fortimber and has become naturalized in some areas outside its native range. It can be found growing successfully inBismarck, North Dakota,[19] and it is sold as far south asOkeechobee. The American sycamore is also well adapted to life in Argentina and Australia and is quite widespread across theAustralian continent, especially in the cooler southern states such asVictoria andNew South Wales.
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.[20] It is a fast-growing, early-mid successional hardwood tree species.[21] 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.[22] 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.[20]
As one of the largest trees in the wet bottomland habitats where it dominates, it is a key component of the structure of those habitats.[23] 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.[22] The largest hollow trees can be big enough for black bear dens, but average trees create homes for bats and cavity-nesting birds like wood ducks, barred owls, screech owls, chimney swift, and great-crested flycatcher.[23]
American sycamore is the host plant of thesycamore tussock moth, a species which specializes in it, and a major host plant for the drab prominent moth.[23] This plant is also the first host known forPlagiognathus albatus.[24]
The American sycamore is able to endure a big city environment and was formerly extensively planted as ashade tree,[12] but due to the defacing effects ofanthracnose it has been largely usurped in this function by the resistantLondon plane.[25]
Its wood has been used extensively forbutcher'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.[25]
Investigations have been made into its use as abiomass crop.[26]
The tree bark has traditionally been used by Native Americans to make little dishes for gatheringwhortleberries.[27]
The American sycamore is a favored food plant of the pestsycamore leaf beetle.
American sycamore is susceptible to planeanthracnose disease (Apiognomonia veneta, syn.Gnomonia platani), an introduced fungus found naturally on theOriental planeP. orientalis, which has evolved considerable resistance to the disease. Although rarely killed or even seriously harmed, American sycamore is commonly partiallydefoliated 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.[28]
As a result of the fungus' damage, American sycamore is often avoided as a landscape tree, and the more resistantLondon plane (P. × hispanica; hybridP. occidentalis × P. orientalis) is planted instead.
The terms under which theNew York Stock Exchange was formed are called the "Buttonwood Agreement", because it was signed under a buttonwood (sycamore) tree at 68Wall Street,New York City in 1792.
The sycamore made up a large part of the forests of Greenland and Arctic America during theCretaceous andTertiary periods. It once grew abundantly in central Europe, from which it has now disappeared.[12] It was brought to Europe early in the 17th century.[29]
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