BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Platanus occidentalis | Sycamore 



GENERAL BOTANICAL CHARACTERISTICS : 
Sycamore is a native, deciduous tree. Although not the tallest, it is
amoung the tallest trees of eastern deciduous forests [78].  Mature
heights range from 60 to 120 feet (18-37 m) [9,83].  Reported diameters
range from 2 to 6.6 feet (0.6-2 m) [83].  The bark of young trunks has
small scales.  Bark at the base of large trunks is deeply furrowed and
up to 3 inches thick (7.6 cm) [83]; on the upper portions of the trunk
the bark exfoliates in patches, leaving areas of inner bark exposed
[30,78].  The leaves are 4 to 10 inches (10-25.4 cm) long, often as
broad or broader than they are long [83].  Sycamores form widespread,
strongly branched root systems [78].  The fruit is a plumed achene [52];
numerous fruits are tightly aggregated into a ball-shaped fruiting head
0.8 to 2 inches (2-5 cm) in diameter [9,13].

Sycamore is characterized by rapid growth throughout its life; it is
also long lived (over 250 years) [78].

A sycamore measuring 140 feet (43 m) tall and 120 inches (305 cm) dbh
has been reported; a specimen from Indiana was reported as 168 feet (51
m) tall and 33 feet (10 m) in circumference.  Open-grown individuals can
achieve a crown spread of 100 feet (30 m) or more [78].  A survey of big
trees in seven mid-southern states reported that the second and fourth
largest trees (of all species) were sycamores.  The largest sycamore in
these states was a Tennessee tree 140 feet tall (42.67 m) and 65.9
inches (167.4 cm) dbh, with a circumference of 207 inches (525.8 cm),
the largest circumference of any tree in these states [53].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Sycamore is monoecious.  Plantation-grown sycamores are usually sexually
mature in 6 to 7 years.  Natural stands of sycamore usually produce
appreciable numbers of seed at approximately 25 years; optimum seed
production occurs from 50 to 200 years of age.  Seed production is not
dependable from trees over 250 years old.  Good seed crops are produced
every 1 to 2 years [78].  Sycamore seeds are dispersed by wind and water
[83].  They have a relatively rapid rate of descent for light seeds; the
estimated lateral travel distance in a 6 mile per hour (10 km/hr) breeze
is 223.7 feet (62.8 m) [52].  Since seed dispersal occurs at a time of
year when water levels are declining after spring floods, water
dispersal often results in seed deposition on muddy flats that are
highly conducive to germination [44,83].  

Sycamore seeds do not require any pretreatment for good germination [9].
They do require very moist conditions for good germination and are
tolerant of inundation [83].  Soaking seeds in water for up to 32 days
did not reduce germination rates; the seeds did not germinate during the
soaking period [40].  Sycamore seeds germinated at a significantly
higher percentage in light than in dark [54]; they do not germinate well
in heavy litter or in deep shade [78].  Sycamore seeds did not germinate
in laboratory tests at temperatures lower than 59 degrees Fahrenheit (15
deg C); they germinated well at temperatures between 59 and 86 degrees
Fahrenheit (15-30 deg C), with maximum emergence at 68 degrees
Fahrenheit (20 deg C) in the wetter part of a moisture gradient [18].

Sycamore seedlings require direct sunlight for good growth and
establishment [78].  At the end of their first year, sycamore seedlings
on clay soil showed better height growth in partial shade than in full
sun.  On alluvial soil or loess, height growth was better in full sun
[7].  Seedling roots penetrate the soil quickly and grow deeper in loess
soils than in alluvial or clay soils [78].

Young sycamore stems sprout readily from the stump; sycamore is not a
vigorous epicormic sprouter.  Sycamore can be vegetatively propagated by
cuttings [78].


SITE CHARACTERISTICS : 
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].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Sycamore is intolerant of shade.  Seedling growth is greatly reduced in
deep shade (defined as 5 percent of full sunlight) [45].  Sycamore
occurs in forest types that are pioneer, transitional, subclimax, and
climax [31,78].  

Sycamore will pioneer on sand and gravel bars and other newly formed
land, often persisting through later seres, such as sugar maple (Acer
saccharum)-bitternut hickory (Carya cordiformis), particularly on wet
sites [78].  It is an occasional pioneer on upland oldfield sites,
particularly in the central parts of its range.  In Illinois, sycamore
was the most common tree species present in the seed rain or as
seedlings in local old fields [18].

In southern Illinois, 1- to 5-year-old sycamore seedlings were most
common on newly formed land, then on old fields, in cottonwood-willow
communities, and in soft mixed-hardwoods (elms, ashes, birches [Betula
spp.], silver maple, and red maple [Acer rubrum]); there were no
seedlings present in hard mixed-hardwood communities (oaks and
hickories) [85].  Sycamore usually replaces willows (Salix spp.) and
eastern cottonwood (Populus deltoides).  The sycamore-sweetgum-American
elm type usually succeeds cottonwood on river fronts, but may pioneer on
heavily cutover sites or old fields in bottomlands.  This type may
persist as a subclimax type where repeated disturbances such as flooding
occur.  It is usually succeeded by swamp chestnut oak (Quercus
michauxii)-cherrybark oak or sweetgum-willow oak (Liquidambar
styraciflua-Q. phellos) [31].  In the North Carolina Piedmont, sycamore
and river birch (Betula nigra) usually replace alders (Alnus spp.) and
willows on small islands or spits in streams after the land becomes
stable and moderately well drained [78].  Sycamore and river birch are
usually followed by elms (Ulmus spp.), ash (Fraxinus spp.) and red maple
[78].  In Kentucky, an island that formed in 1913 was occupied by a pure
stand of eastern cottonwood 30 to 40 feet tall by 1922.  Trees coming in
among the cottonwoods included sycamores [67].

The presence of sycamore in upland climax forests may be a function of
disturbance rather than a function of moisture or drainage regime; its
establishment in these woods may require larger disturbances than those
produced by single or multiple tree falls [8].


SEASONAL DEVELOPMENT : 
Sycamore flowers appear in May in the northern parts of its range, and
as early as late March in the South.  Late spring frosts will kill
flowers, leaves, and twigs [78].  The fruits ripen from September to
October or November, and usually remain on the tree over winter,
breaking up or falling off the following spring from February through
April [9,78].

Related categories for Species: Platanus occidentalis | Sycamore