American Sycamore (TVA, White's Creek Small Wild Area, Plants)

American Sycamore

Platanus occidentalis

Summary ⁹

Platanus occidentalis, also known as American sycamore, American planetree, occidental plane, and buttonwood, is one of the species of Platanus native to North America. It is usually called sycamore in North America, a name which can refer to other types of tree in other parts of the world.

Adaptation ¹⁰

It often is a pioneer on upland sites in the central part of its range, but it is primarily a species of bottomland and alluvial soils, also occurring on creek banks, mesic coves and lower slopes, on a wide range of soil types. It is a major pioneer species in the floodplains of large rivers and occurs on a variety of wet sites, including shallow swamps, sloughs, and wet river bottoms where soil is saturated 2-4 months during the growing season. Water dispersal often results in seed deposition on muddy flats highly conducive to germination because seed dispersal occurs when water is receding after spring floods. American sycamore is most commonly found in mixture with sweetgum, boxelder, silver and red maple, cottonwood, and willows. It is found at 0-300 (-750) meter elevation.

American sycamore can tolerate weeks of flooding, even complete submersion of seedlings, provided that the water is aerated. A significant portion of young sycamores can survive almost 2 months of continuously waterlogged soils during dormancy, but sycamore of various stages will die if the entire tree is inundated for more than two weeks during the growing season. Saplings top-killed by flooding may resprout from the root crown.

Flowers appear with the leaves in April-May or as early as late March in the South. Fruits ripen September-October (-November), usually breaking up and falling from the tree through the winter and into spring.

Associated forest cover ¹¹

Sycamore grows singly or in small groups with other trees but seldom in extensive pure stands in the northern part of its range. In the Mississippi bottom lands of the South, however, it does grow in pure stands of 16 to 40 ha (40 to 100 acres). Sycamore is the predominant tree in two forest cover types (7). In River Birch-Sycamore (Society of American Foresters Type 61) the associate trees include sweetgum (Liquidambar styraciflua), eastern cottonwood (Populus deltoides), red maple (Acer rubrum), black willow (Salix nigra), and other moist-site hardwoods. This type is widespread, occurring in southern New England, southern New York, New Jersey, Pennsylvania, southern parts of the Lake States, and south into Oklahoma, Missouri, and Tennessee. It is also found in the Allegheny and Piedmont Plateaus of the Appalachian Mountains.

In Sycamore-Sweetgurn-American Elm (Type 94), the chief associates are boxelder (Acer negundo), green ash (Fraxinus pennsylvanica), sugarberry (Celtis laevigata), silver maple (A. saccharinum), eastern cottonwood, black willow, water oak (Quercus nigra), Nuttall oak (Q.nuttallii), sweetgum, and river birch (Betula nigra). This type is found throughout the southern part of the range of sycamore, usually on the alluvial flood plains of major rivers. A Sycamore-Pecan-American Elm valiant type is found on river fronts in the Mississippi River Valley. A comprehensive survey of mixed hardwood species conducted in 14 Southeastern States by North Carolina State University showed that sycamore comprised 0.1 percent of the total basal area on wet flat sites, from 0.5 to 8.8 percent on various classes of bottom-land sites, 0.7 percent on lower slope coves, and 0.1 percent on upland slopes and ridges (26).

Other forest types with which sycamore grows are Black Ash-American Elm-Red Maple (Type 39) in the northern part of the sycamore range, Sugarberry-American Elm-Green Ash (Type 93) in the South, Sweetgum-Yellow-Poplar (Type 87) in the Atlantic Coastal Plain and Piedmont, and Black Willow (Type 95), which grows throughout the range of sycamore.

Sycamore is also an important tree in Cottonwood (Type 63), a valuable pioneer type, characteristic of fronts on all major streams in the South except in sloughs and swamps (21).

Associations ¹²

Foodplant / saprobe
acervulus of Discula coelomycetous anamorph of Apiognomonia errabunda is saprobic on fading, attached leaf of Platanus occidentalis
Remarks: season: 8-9
Other: major host/prey

Damaging agents ¹³

Many insects feed on sycamore but none are of economic importance in forests. Some may, however, seriously damage individual trees planted for landscaping purposes. Probably the insects that attack sycamore do not kill healthy trees, but when they attack a tree of reduced vigor, they may cause severe injury or death. The more important insects are the sycamore lacebug (Corythuca ciliata), the flathead sycamore-heartwood borer (Chalcophorella campestris), and the sycamore tussock moth (Halisidota harrisii). Other insect enemies include leaf feeders and hoppers, periodical cicada (Magicicada septendecim), aphids, scales, crosswood borers, flatheaded borers, roundheaded borers, bark borers, darkling beetles (Tenebrionidae), ambrosia beetles, moths, and caterpillars, leaf rollers, and horntails (Siricoidea). Sycamore is also subject to ant attacks, which often cause ingrown bark pockets that reduce the quality of the wood (21).

Diseases of sycamore have become more important with its increased culture in plantations. In the mid-1970's, potentially serious infection involving leaf scorch, dead branches, top dieback, and lethal cankers occurred in Illinois and adjacent States (22).

A 1973 survey of 26 plantations in Tennessee, Mississippi, Louisiana, and Alabama revealed leaf scorch, top dieback, and lethal bole cankers in four bottom-land plantations (9). In two progeny tests in Mississippi the same symptoms were evident, so severely in one test that it was a total loss within 5 years (5). The primary organism causing lethal bole cankers has not been established. A complex of organisms seems to be involved, but Ceratocystis fimbriata and Botryodiplodia theobromae are prime suspects. When seedlings were inoculated with either of these organisms by the bark-flap technique, cankers developed on the stem within 30 days; when 8-year-old trees were inoculated with Ceratocystis fimbriata, cankers appeared and some trees died within a year (19). Temperature also seems to be a factor (15,16,17). Acremonium diospyri has also been identified in trees displaying these symptoms.

Sycamore is susceptible to anthracnose, the same disease that attacks oaks (21). This fungus attacks in the spring and sometimes completely defoliates the trees. Severe attacks also kill twigs, and frequently cankers are formed up to 25 mm (1 in) in diameter. Usually, a second set of leaves is produced following defoliation and few trees die from an attack. Anthracnose may weaken a tree, however, making it susceptible to attack by other diseases. Heavy attacks by this disease also reduce radial and terminal growth. Sycamore is host to the eastern mistletoe (Phoradendron spp.) but damage usually is not serious.

Weather damage and damage caused by insects and disease are commonly confused. For example, anthracnose attacks are often mistaken for frost damage. Although low winter temperature may injure the cork cambium and cause the outer bark to be sloughed off, the health of the tree is not affected. Late spring frosts may kill sycamore buds over a wide area, and where this occurs, the damaged trees characteristically have long dead twigs with bushy masses of leaves around their bases by midsummer.

A limited study of sycamore shade trees following a sleet storm in west-central Illinois indicated that the tree is susceptible to ice damage (21). But in forest stands, it is seldom damaged by such storms.

Because it develops a widespread, strongly branched root system, sycamore is a windfirm tree. However, large sycamores are likely to develop windshake, a wood defect that reduces their value for lumber and other products.

Genetics ¹⁴

Genetic experiments with sycamore in the eastern United States have demonstrated heritable variation in growth and other traits (8,13,24,29,31). Tree improvement programs are in progress (20) and genetic gains in early growth rate have been obtained (13,31).

Geographic variation in sycamore is extensive, and, noted in many other widely distributed species, trees of southern origin have a potential for faster growth than trees of more northern origin when planted near or slightly north of their point of origin (8,13,24,29,31).

Sycamore is unique among North American tree species in displaying a strong north-south gradient in resistance to a killing stem canker disease. In two progeny tests of half-sib families selected along the Mississippi and Chattahoochie Rivers, families of northern origin (Missouri and northern Georgia) were attacked much more severely than were families from farther south (southern Georgia and Louisiana) (5).

Two varieties of sycamore have been named in addition to the typical variety. P. occidentalis var. glabrata is common in western Texas and Mexico but is considered by some taxonomists to be synonymous with the typical variety. P. occidentalis var. attenuata is apparently intermixed with the typical variety, but its status is in need of clarification. The London plane of the Old World, P.x acerifolia, is considered a collection of advanced generation hybrids and backcrosses between P.orientalis and P.occidentalis (12). London plane is an important street tree in cities of the United States and Europe because of its resistance to diseases and especially the air pollution found in the urban environment.

Habitat characteristics ¹⁵

More info for the term: tree

Sycamore is primarily a species of alluvial soils along streams and in
bottomlands, but occurs occasionally as a pioneer on drier upland slopes
[13,30.78]. It occurs on a wide variety of soils, including both sands
and clays [57]. Its best growth occurs on sandy loams or loams with a
good supply of ground water but it also occurs on wet muck, shallow peat
and other, more poorly drained bottomland soils [78].

Sycamore occurs on a variety of wet sites, including shallow swamps,
sloughs, and very wet riverbottoms where soil is saturated 2 to 4
months during the growing season [39]. Sycamore seedlings survived
almost 2 months of continuously waterlogged soils [46]. In a greenhouse
experiment, after experiencing 60 days of completely waterlogged soils,
about half of current-year seedlings died shortly after their removal
from the water; none died with shorter treatment periods [41]. Sycamore
is more tolerant of poorly drained soils in the northern parts of its
range. It was given an adaptation value of 7.5 (out of a maximum of 10)
for moisture tolerance [1]. Sycamore has a recommended lower pH range
of 4.0 to 4.5 [77]

Sycamore is rated as moderately tolerant of flooding. In the Northeast,
sycamore occurs on sites with greater than 98 percent probability of
flooding in any given year [56]. In Illinois, sites that experience
flooding approximately 3 months of the year are dominated by silver
maple, sycamore, and green ash (Fraxinus pennsylvanica var. lanceolata).
These sites are usually flooded before the growing season; sycamore is
intolerant of flooding during the growing season and will die if the
entire tree is inundated for more than 2 weeks [78]. Saplings may be
more resilient than mature trees due to their higher sprouting capacity;
Baker [4] reported that even though 4 weeks of flooding appeared to have
killed 65 percent of sycamore saplings, 90 percent of the saplings were
alive at the end of one growing season following flooding. Most of them
had only been top-killed and subsequently sprouted from the root crown
[4]. Seedlings are less tolerant of flooding than larger plants simply
because they are more likely to be completely covered by water during
active growth. Only 28.8 percent of scyamore seedlings survived
complete inundation for 5 days during a June flood as compared to a
survival rate of 88.9 percent for unflooded seedlings [46].

The elevational range of sycamore extends from sea level to 1,000 feet
(305 m) in the northern parts of its range and to 2,500 feet (762 m) in
the southern Appalachians [13,78].

Habitat: plant associations ¹⁶

More info on this topic.

This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

K098 Northern floodplain forest
K099 Maple - basswood forest
K100 Oak - hickory forest
K101 Elm - ash forest
K103 Mixed mesophytic forest
K106 Northern hardwoods
K112 Southern mixed forest
K113 Southern floodplain forest

Importance to livestock and wildlife ¹⁷

Sycamore does not provide much food for wildlife, although the seeds are
eaten by some birds including the purple finch [82,84], goldfinch,
chickadees, and dark-eyed junco [84], and by muskrat, beaver, and
squirrels [13,76,82,84]. Sycamore is rated as medium in suitability for
waterfowl habitat and low in suitability as deer or turkey food [3].
Carey and Gill [19] rated sycamore as only fair (their lowest rating)
for wildlife use. In Arkansas, sycamore is of minor importance as deer
browse [84]. As sycamores age, they may develop hollow trunks which
provide shelter for a number of wildlife species; some large, old
individuals have formed cavities large enough to be used as dens by
black bear [84]. Cavity nesting birds include the barred owl [2],
eastern screech-owl, great crested flycatcher [37], and chimney swift
[84]. Wood duck use sycamores as nest trees [29].

The bottomland forests in which sycamore occurs are very important
wildlife habitat, sheltering numerous animal species including wood
duck, other waterfowl, upland game birds, and deer [57]. In Indiana,
riparian forests in which sycamore occurs are important habitat for the
endangered Indiana bat, which uses these areas for nursery colonies
[10].

Key plant community associations ¹⁸

More info for the term: natural

Sycamore is found in quantity only in bottomland forests, particularly
of elm-ash-cottonwood (Ulmus spp.-Fraxinus spp.-Populus deltoides) types
as defined by Shifley and others [66], and cottonwood-willow (Salix
spp.) types. It usually occurs singly or in small groups [78].
Sycamore is found occasionally along intermittent streams within upland
stands of oak-hickory (Quercus spp.-Carya spp.) communities. It is a
major pioneer species in the floodplains of large rivers [74]. In the
Southeast pure stands of 40 to 100 acres (16-40 ha) are sometimes
formed; it rarely forms extensive pure stands in the northern parts of
its range [78]. In the northern states sycamore is rarely the dominant
species; it increases (replacing silver maple [Acer saccharinum]) with
decreasing latitude [27].

Sycamore is listed as a dominant or indicator species in the following
publications:

1) The natural forests of Maryland: an explanation of the vegetation map
of Maryland [14]
2) The natural communities of South Carolina [58]
3) Land Classification in the Blue Ridge province: state-of-the-science
report [55]
4) Forest management of floodplain sites in the northeastern United
States [56]
5) Management of bottomland hardwoods [61]
6) Ecological communities of New York State [63]
7) Classification and evaluation of forest sites on the northern Cumberland
Plateau [68]
8) Classification and evaluation of forest sites on the Natchez Trace State
Forest, State Resort Park, and Wildlife Management Area in west
Tennessee [69]

Nutritional value ¹⁹

The nutritional value of sycamore "grab samples" was reported as
follows: 25 percent dry matter, 13.7 percent crude protein, and 67
percent total digestible nutrients [17]. Foliage samples were 18.2
percent lignin, 2.67 percent calcium, 0.38 percent magnesium, 0.12
percent phosphorus, and 1.65 percent potassium [65].

Other uses and values ²⁰

More info for the term: tree

Sycamore is planted as a street tree [83], although it is highly
susceptible to ozone damage [25] and is susceptible to foliar injury and
reduced growth when exposed to salt spray [73]. The London plane tree
is more resistant to air pollutants and is more commonly planted as a
street tree [28].

Sycamore has been planted in shelterbelts [16].

Sources and Credits

Pierre-Joseph Redouté, no known copyright restrictions (public domain), http://commons.wikimedia.org/wiki/File:T2_02_Platanus_occidentalis_par_Pierre-Joseph_Redout%C3%A9.jpeg
(c) José María Escolano, some rights reserved (CC BY-NC-SA), http://www.flickr.com/photos/valdelobos/8235061672/
(c) prof. Bizzarro, some rights reserved (CC BY), https://www.flickr.com/photos/bazardelbizzarro/15421234446/
(c) LadyDragonflyCC - >;<, some rights reserved (CC BY), https://www.flickr.com/photos/ladydragonflyherworld/8659196986/
(c) eccentricvirgo, some rights reserved (CC BY-NC-ND), https://www.flickr.com/photos/8169662@N08/16905455026/
(c) "<a href=""http://www.knps.org"">Kentucky Native Plant Society</a>. Scanned by <a href=""http://www.omnitekinc.com/"">Omnitek Inc</a>.", some rights reserved (CC BY-NC-SA), http://plants.usda.gov/java/largeImage?imageID=ploc_001_avd.tif
(c) John Hilty, some rights reserved (CC BY-NC), http://www.illinoiswildflowers.info/trees/photos/am_sycamore3.jpg
(c) Jeff Turner, some rights reserved (CC BY), http://commons.wikimedia.org/wiki/File:American_sycamore_(Platanus_occidentalis)_2.jpg
Adapted by Jonathan (JC) Carpenter from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Platanus_occidentalis
Public Domain, http://eol.org/data_objects/1391026
(c) Unknown, some rights reserved (CC BY-NC), http://eol.org/data_objects/22778977
(c) BioImages, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/22922610
(c) Unknown, some rights reserved (CC BY-NC), http://eol.org/data_objects/22778985
(c) Unknown, some rights reserved (CC BY-NC), http://eol.org/data_objects/22778986
Public Domain, http://eol.org/data_objects/24642656
Public Domain, http://eol.org/data_objects/24642645
Public Domain, http://eol.org/data_objects/24642649
Public Domain, http://eol.org/data_objects/24642647
Public Domain, http://eol.org/data_objects/23370420
Public Domain, http://eol.org/data_objects/24642651

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