American Sycamore
Platanus occidentalis

Location in Ontario
American Sycamore, a Carolinian Tree, grows in small pockets throughout the Carolinian Zone of the Deciduous Forest Region. It grows on rich soils along creeks and rivers. It will also grow on poorly drained soil, such as in swamps.


Tall Sycamore growing along Big Creek in Norfolk County


Genus Platanus
These are tall trees commonly known as plane trees, referring to the large or broad leaves. The hybrid London Plane Tree (see Genetics below) has been planted throughout the world. In England, Sycamore refers to Sycamore Maple, which is in the Acer family (Acer Pseudoplatanus).

Visit this
site for information on the Sycamore Maple.

Platanus leaves are alternate and simple with lobes. Trees are monecious, with male and female flowers in separate round aggregates. The fruit is a group of achenes within the aggregate ball. The bark is distinctive, peeling off readily to produce a mottled scaly appearance. The only Sycamore that occurs naturally in Canada is American Sycamore sometimes called American Plane Tree.

 
In the Landscape
American Sycamore is a very large tree that can reach over 30 metres in height and live more than 250 years! The diameter can be 2 metres or more. Sycamore is a relatively fast growing, showy tree with unusual mottled bark and spherical seed aggregates which persist on the branches into winter.

TREE FACT: This is the largest hardwood in Ontario by bulk (considering height and width).

TREE FACT: American Sycamore is also known as "Buttonwood", referring to the fact that Sycamore wood was used to make buttons in pioneer days.


A Heritage Tree, Chatham-Kent. This huge tree is over 200 years old.
  

You can see from this photo how it was possible for early settlers to make a table from a cross-section slab of the trunk! At one time Sycamore trees like this one were common in Southern Ontario.

Leaves
The leaves leaves have 3 or 5 lobes. The edges have large wavy teeth. Leaves turn yellow in the fall.
Bark
The bark is mostly smooth and brownish, but has large thin pieces flaking off to show a whitish colour beneath. This gives the tree a mottled or blotchy look.
Flowers
Sycamore trees are monoecious with male (pollen) flowers and female (seed) flowers on the same tree. Pollen flowers are inconspicuous, yellowish-green and clumped together in a ball-like structure (aggregate). Seed flowers are grouped together in a reddish aggregate. Flowers appear in May with the leaves and are pollinated by the wind.
Fruit
Individual seeds are achenes (hairy, tufted mini-nuts). Seeds are yellowish, hairy and club-shaped. Seed aggregates hang on the tree into winter. Seeds are produced every year after 10 years of growth, but are sensitive to late frosts.
 

 TREE FACT: American Sycamore is susceptible to anthracnose which causes die-back. However, it can undergo photosynthesis in its bark which allows the tree to survive (the bark often has greenish patches).

Wood
The wood is medium hard, but weak.
Specific gravity: 0.49
Janka Hardness: 770 lb
Wood Comparison Chart
The wood is used for cabinets and wood trim. Early settlers used a slab from the trunk of a large tree to make a cutting block. The slab was sanded smooth and legs were added.

Genetics
American Sycamore (Platanus Occidentalis) forms a hybrid with Oriental Sycamore (Platanus Orientalis) known as "London Plane Tree" (Platanus × acerifolia). It is similar to American Sycamore, but is a smaller tree with leaves that are more indented. Also, seed aggregates occur in pairs rather than singly. Finally, the bark is less white in colour and the tree is very resistant to pollution, making it favoured for street plantings.

Visit this site for a comparison of the leaves of
Platanus.


Seed aggregates hanging on the tree in winter.


A line of Sycamores in winter along Highway 24, Norfolk County

Link to United States Forest Service Silvics Manual for American Sycamore.

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