The six different species of buckeye trees native to North America all belong to the Hippocastanaceae family, a group of plants that also includes the horsechestnut tree. The buckeyes feature palmate compound foliage, with leaves composed of multiple leaflets arranged at the end of a stem in the shape of a hand. Flowers hanging in clusters and inedible, poisonous nuts are also characteristics of the buckeyes.
Growing wild from the central Midwest southward to states like Arkansas and Mississippi, Ohio buckeye, Aesculus glabra, develops between 20 and 40 feet. It has five leaflets on each leaf, with the dark green colors going to shades of yellow in fall. Ohio buckeye is a good fit for naturalized areas, since it creates quite a mess – as do the other buckeyes – with its twigs, fallen foliage and fruits.
Painted buckeye, Aesculus sylvatica, is a native of the northern portions of the Deep South, growing to 20 feet. It has flowers that emerge in early spring that may be different colors, hence the tree's name. They vary from red to yellow, growing in clusters that can reach 7 inches long. Painted buckeye usually has five leaflets on each leaf, but can sometimes have as many as seven.
Yellow buckeye, Aesculus octandra, is the largest of the buckeye trees, notes the "National Audubon Society Field Guide to Trees: Eastern Region," averaging 80 feet tall. Also called sweet buckeye, its leaves possess between five and seven leaflets that are as long as 8 inches. Yellow buckeye is native from Pennsylvania south to Georgia and Alabama, with its distribution extending west to southern Illinois.
The red buckeye, Aesculus pavia, is the most southerly of the buckeye group in the United States, growing into the warmth of Florida, the Gulf Coast and Texas. It is a big shrub or small tree, with those in the wild no larger than 30 feet and cultivated individuals between 8 and 12 feet tall. Red buckeye has five leaflets per leaf, shows no significant fall color and it loses its foliage as early as September, notes the University of Connecticut Plant Database. It generates clusters of showy red flowers in May that make it a worthwhile addition to the landscape.
The Texas buckeye, Aesculus arguta, responds to drought conditions by dropping its foliage early. Growing from eastern Kansas south through Oklahoma and into northern Texas, the species has as many as 11 leaflets per leaf. It is usually only about 20 feet high, but some can reach 40 feet tall. It is a close relative and perhaps an offshoot of the Ohio buckeye species.
The California buckeye, Aesculus califronica, grows only in the Golden State, to around 23 feet at the most. This small tree of hilly and mountainous terrain has from four to seven leaflets on each leaf. Its clusters of flowers are white to a pale shade of red, turning out on the ends of the branches. They yield a pear-shaped capsule that contain up to six toxic seeds.