Mostly planted as ornamental, shade and street trees, elms (Ulmus spp.) are typically medium to large trees with a vase-like canopy. All elm species are very similar in their characteristics, making it difficult to tell the species apart. In spring, you'll be able to study most of the elm tree's features to make the identification, however, because the leaves will have emerged. Elm tree species are native to North America, Europe and parts of Asia.
Identify elm trees in spring by studying the tree's size and shape. The American elm (U. americana) grows up to 100 feet tall or larger with a distinct, vase-like shape, while the Chinese or "lacebark" elm (U. parvifolia) is also vase-shaped but grows to only 60 feet tall. The Siberian elm (U. pumila) can grow up to 130 feet, but it has a wide-spreading, compact canopy, while the camperdown elm (U. glabra camperdownii) grows up to only 15 feet tall and has a distinct weeping form.
Study the leaves to identify the elm tree. Most elm tree leaves are 3 to 7 inches long, don't have lobes and are edged with fine, double teeth. But the lacebark elm has the smallest leaves of the elm species, growing to only ¾ to 2 inches long and with dark-green, glossy upper surfaces. The winged elm's (U. alata) leaves are also smaller, about 1½ to 3 inches long.
Identify the elm tree by whether it's blooming or fruiting in spring. The cedar elm (U. crassifolia) may start blooming in its light-green flowers as early as late spring, but it usually doesn't flower until early summer. But you'll see the single-winged, oval or circular fruits that are green in spring and favorite foods of Passenger Pigeons on the slippery elm tree (U. rubra).
Look at the bark to identify the elm tree. The rare rock elm tree (U. thomasii Sarg.) has corky ridges on its branches, while the Siberian elm has gray, rough bark. Unlike other elms that have ridged and furrowed bark, the lacebark or Chinese elm has mottled brown bark that sheds in thin flakes to expose orange or reddish inner bark.
Identify the elm tree in spring by where it's growing. The cedar elm is a popular street tree in the desert southwest United States, while the American elm is commonly found in the Midwest United States and Canadian prairies. Although native to Europe and western Asia, the Scotch elm (U. glabra Huds.) is found in urban areas of eastern North America, and the lacebark elm is a desirable street tree in most parts of the United States.