Identifying characteristics:
The sycamore is one of the largest broadleaf trees in North America,
and can reach a height of 115 feet. It has a massive trunk, a broad, open,
often irregular crown with massive, crooked branches. The palmately-lobed
leaves (3 to 5 lobes) are simple,
alternate and large (4 to 7 inches long), with coarsely-toothed margins.
Leaves are very hairy when young, becoming smooth and bright green above
and paler and smooth beneath, with a few hairs along the veins. In spring,
at the base of each leaf stalk, a prominent stipule encircles the twig.
Fall color is disappointing, with leaves turning a dull yellow, browning
before they fall. When the leaves unfold in late spring, the tiny flowers appear, crowded in small, dense,
ball-shaped heads. Male and female flowers are produced on separate shoots
on the previous year's growth. The fruits
(achenes) are borne in a 1-inch-diameter, aggregate ball on a slender stalk.
The balls remain on the tree into winter, slowly disintegrating and allowing
the seeds to be dispersed. Twigs are marked by the stipule scars
which form a ring around each node. Leaf scars completely encircle
the buds, with 5 to 9 bundle scars. The buds, hidden in the base
of the leaf stalk, are bluntly conical and are covered with 3 scales. The
outer scale is glabrous, the second is green and gummy and the innermost
scale is covered with rust-colored hairs. A terminal bud is absent. The
trunk and upper branches are impressively mottled where thin, irregular
patches of brown bark fall away to reveal
the white inner bark. The lower trunk is covered with gray or reddish-brown
plates.
Similar species:
- Norway maple (Acer platanoides)
- London plane (Platanus X acerifolia)
Ecology:
Distribution: This tree is common throughout eastern North
America and is scattered in the mountains of northeastern Mexico. It is
native or has naturalized throughout the southern one-half to two-thirds
of Iowa. If planted in northern Iowa, it suffers twig dieback during severe
winters.
Habitat: The sycamore is a lowland tree, tolerant of poorly-drained soils along rivers and streams and on floodplains. It reaches its full stature in deep, moist, rich soils, but in low, wet areas its growth is less robust. It will invade abandoned fields and spoil banks and is moderately shade tolerant. A major drawback to its use as an ornamental is that it is highly susceptible to anthracnose, a fungus disease. The effects seem to be exacerbated by cold, wet spring weather immediately after leaf emergence. Although the tree will lose the infected leaves and produce more later in the season, the disease weakens its resistance to pests, diseases and winter injury. Fungicide treatments and sanitation may alleviate the problem. Sycamore plant bug, sycamore tussock moth, borers, scale and bagworm are sometimes problematic.
Uses:
Wood: The wood is light brown, hard, moderately heavy and
shock-resistant. Because it is coarse-grained and hard to split, it is often
used for butcher's blocks. Other uses include flooring, veneer, boxes, crates,
pallets and inner parts of furniture.
Wildlife: The sycamore is of little food value to wildlife. The seedballs are utilized by squirrels and small rodents. The purple finch is the only bird that eats the seeds to a large extent. Beaver and fox squirrel feed on the bark. Old trees are often hollow and form important nest cavities and dens.
Horticulture: This tree is a faster grower than most native trees, with the exception of the poplars and the silver maple. This attractive tree is often planted as an ornamental in Iowa as it is more long-lived and has stronger wood than most other fast-growing trees. Although it is an impressive tree, its large size and the messiness of falling leaves, fruit and twigs may be a disadvantage. The London plane (Platanus X acerifolia), sometimes planted in the state, is a cross between this species and an oriental species. Its leaves are more deeply lobed and the seedballs occur in groups of 2 or 3, rather than solitary.
