Buckeye is defined in the Oxford English Dictionary as:
An American tree or shrub related to the horse chestnut, or the shiny brown nut of such a tree or shrub.
An orange or brown New World Butterfly with conspicuous eyespots on the wings.
(informal) A native of the US State of Ohio.
In parts of North America, Europe and Asia, similar (but not the same) chestnut-bearing trees can also be found.
Timber taken from the buckeye tree is clean and white if cut when the sap is down in the winter. As it isn't strong or durable when exposed to the elements, the timber is used mainly in the construction of wooden toys and other small timber projects. The wood from this versatile plant is also used as pulp to make paper - hence the presence of the Mead paper-mill in the small south-central Ohio town of Chillicothe.
Plentiful in Ohio
The buckeye lends its name to the state of Ohio, USA, through the sheer proclivity of the tree throughout the state. The Ohio buckeye has palmate1 leaves featuring five oval or oblong-obovate leaflets that grow from three to six inches in length. Emitting a foul odour when crushed, these leaves change to a brilliant orange in autumn (fall). The buckeye tree produces spikes of greenish-yellow flowers which are followed by tough, round pods growing anywhere from one inch to two or three inches in diameter. They are typically not spherical, so it depends on which axis you take your measurement from - older trees produce larger pods. The pods usually contain one (sometimes two or three) large, smooth, shiny brown nuts (similar to conkers) that can range from half an inch in diameter to well over an inch. All parts of the plant are poisonous to humans if eaten. The nuts contain aesculin, which induces vomiting and in extreme cases, paralysis.
The Buckeye has been the mascot of the Ohio State University since 1950. This long-standing link, perhaps through the University's good reputation (or the travels of the athletic teams), has played its part in popularising for other people the fact that residents of the state of Ohio revel in being called Buckeyes - a tag worn with pride since Civil War days.