The leaves are palmately compound with five (rarely seven) leaflets, 8–16 cm (3.1–6.3 in) long and broad. The flowers are produced in panicles in spring, yellow to yellow-green, each flower 2–3 cm (0.79–1.18 in) long with the stamens longer than the petals (unlike the related yellow buckeye, where the stamens are shorter than the petals). The fruit is a round or oblong spiny capsule 4–5 cm (1.6–2.0 in) diameter, containing one to three nut-like seeds, 2–3 cm (0.79–1.18 in) in diameter, brown with a whitish basal scar.
The Ohio buckeye is the state tree of Ohio, and its name is an original term of endearment for the pioneers on the Ohio frontier, with specific association with William Henry Harrison. Capt. Daniel Davis of the Ohio Company of Associates, under Gen. Rufus Putnam, traversed the wilderness in the spring of 1788, and began the settlement of Ohio. Davis was said to be the second man ashore at Point Harmar, on April 7, 1788. He declared later that he cut the first tree felled by a settler west of the Ohio River, a "buckeye" tree. Additionally, Colonel Ebenezer Sproat, another founder of that same pioneer city of Marietta, had a tall and commanding presence; he greatly impressed the local Indians, who in admiration dubbed him "Hetuck", meaning eye of the buck deer, or Big Buckeye.
Subsequently, "buckeye" came to be used as the nickname and colloquial name for people from Ohio and Ohio State University's sports teams. Ohio State adopted "Buckeyes" officially as its nickname in 1950, and it came to be applied to any student or graduate of the university.
Native Americans blanched buckeye nuts, extracting the tannic acid for use in making leather. The nuts can also be dried, turning dark as they harden with exposure to the air, and strung into necklaces similar to those made from the kukui nut in Hawaii.
Buckeye candy, made to resemble the tree's nut, is made by dipping a ball of peanut butter fudge in milk chocolate, leaving a circle of the peanut butter exposed. These are a popular treat in Ohio, especially during the Christmas and college football seasons.