It's difficult for most trees to tolerate the pollution in city air and the pressure of trampling feet over their roots, so the number of urban species is limited.
There are fewer species growing on streets than in city parks, since the higher population density of trees in parks alters their environment and makes it more hospitable. In this article, we will focus on the identifying features of trees most often found on the streets of eastern cities.
- Trees with Opposite Leaves
Norway maple – Leaves have five blunt-pointed lobes with a few blunt teeth. Bark has deep furrows and ridges that form diamond patterns, as in ash and tulip-tree. A fast-growing European import. Ornamental greenish-yellow flowers in early spring. The Schwedler variant has dark reddish-purple leaves.
Green ash – Compound leaves with 5-9 egg-shaped leaflets, tapering to a point. Tiny greenish, inconspicuous flowers in clusters. Each seed is contained within a single flat membrane, a version of the double, winged “keys” of the maple.
- Trees with Alternate Simple Leaves
Ginkgo – Unique, fan-shaped leaves. Bark is silky to the touch, with an almost flat surface. Female trees drop fruit in fall, with a foul-smelling pulp that contains an edible nut.
Ornamental Pear – Oval, finely toothed leaves. Bark has narrow, vertical furrows and very fine, short horizontal cracks. Usually the first street tree to flower in spring, with small white flowers covering the whole tree. Tiny (under one inch), dry, brown pears appear in fall.
Linden – Heart-shaped leaves with uneven bases. (One variety has leaves that are white beneath.) Long, narrow leaflike bracts bear fragrant off-white flowers in June, smooth. small round seed balls in autumn. Bark is vertically furrowed, without horizontal cracks.
Pin oak – Leaf has 5 pointed lobes with a tiny bristle at the end of each lobe. The lobes tend to occur at right angles to the midrib. Lower branches usually point downward. Rough, non-flaking bark.
London plane tree – Closely related to the sycamore, with bark that peels in patches of yellow, green, and brownLeaves lobed, resembling those of maple but with shallow indentations. Seeds in balls that hang from twigs.
- Trees with Alternate Compound Leaves
Sophora – Also known as Chinese scholartree. Leaves have 7 to 17 egg-shaped or lance-shaped leaflets, each one to two inches long. Light grey, ridged bark. Late summer clusters of yellowish-white flowers shaped like those of pea plants. Pods like strings of beads.
Honey locust - Leaves with many small, narrow leaflets. Thorns over one inch long protrude from the dark brown to black bark. A thornless variety is often planted in cities. Distinctive long, flat, twisting seed pods with smooth, bean-like seeds within.
Ailanthus – Also called Tree-of-Heaven. Leaves with 11-41 leaflets having a small lobe near each leaf base that contains a tiny round gland. Crushed leaves smell like peanut butter. Male flowers occur in large, yellowish clusters that have an unpleasant odor. A fast-growing tree, short-lived, but generates sprouts readily from cut stumps.
