Shape and size

One leader or many

Many conifers keep one straight central trunk to the top, which gives a cone outline. Many broadleaf trees divide their trunk into spreading limbs, which gives a rounded or spreading crown. Elms, especially the American elm, were classically vase-shaped, with limbs arching outwards from a short trunk.

Crown outlines

• Cone or spire: spruces, firs and many other conifers, and sweetgum when young.
• Oval or egg-shaped: sugar maple, red maple and many street trees.
• Round and dense: Norway maple, sugar maple in the open.
• Vase: American elm.
• Wide and spreading: white oak, live oak, and most trees grown in the open.
• Narrow column: some cultivated forms, and aspen in a stand.
• Flat-topped: ponderosa pine and other old pines, and trees on exposed ground.

Open ground or forest

A tree growing alone in a field spreads wide and keeps its lower branches. The same species in a dense wood grows tall and straight, with a small crown at the top. Do not rely on shape alone.

Size as a clue

Size narrows the field but never settles it. Sugar maples and tulip trees can be very tall, while dogwood, redbud and sassafras are small trees of the understorey. A shrubby tree on a windswept ridge may be the same species as a giant in a valley.

Where it is

Note the setting: a damp river bank, a dry slope, a street, a garden. Silver maple, river birch, sycamore and cottonwood favour damp ground. Eastern redcedar and ponderosa pine tolerate drier ground. Planted trees are often from other continents, so a tree that looks out of place may be. A regional field guide or a local arboretum or park service list will tell you which species grow near you.