The horse chestnut is native to southern sections of Europe but now grows in parts of the United States after "escaping" from cultivation in various regions. Imported as an ornamental species valued for its shade, the horse chestnut is not a member of the chestnut family. The species is a close relative of buckeye trees of the central portion of North America. You can identify a horse chestnut tree from its features, some of which are quite distinct.
Estimate the size of a horse chestnut tree to see if it falls within the parameters for the species. This type of tree averages between 50 and 70 feet tall when grown in the open, with a broad and spreading crown of branches.
Examine the leaves of the horse chestnut, looking for a compound leaf composed of seven individual leaflets. The leaf is palmately compound, a botanical phrase describing leaflets arranged like the spokes on a bicycle wheel radiating from the end of a leaf stalk. The leaflets are as long as 10 inches and are broad at the end and narrower at the base. These leaflets attach to a stalk that can be between 3 and 7 inches long, according to the "National Audubon Society Field Guide to Trees."
Look at the color of the horse chestnut leaves in both summer and autumn. The leaves are green in summer but since the tree has the tendency to develop diseases such as leaf scorch, the fall foliage, if any leaves remain on the tree, is usually brown.
Observe the upright clusters of creamy white flowers on a horse chestnut tree. The flowers emerge once the leaves have opened up, usually in bloom by the middle of spring. The flowers have red and yellow spots on them.
Watch as the flowers eventually turn into the nuts of the tree. Horse chestnuts may be by themselves on the tree or grow in clusters. The nut has a surrounding brown husk punctuated with sharp spines. Do not try to eat the nut, as it has a horribly bitter taste. The tree gets its name from the nut, which the Turks at one time employed to make a tonic to prevent horses from coughing.
Study the large buds of the horse chestnut tree in winter to tell the tree apart from other species. The Ohio Department of Natural Resources website says the buds are much larger than nearly any other tree and have a shiny appearance.