Aesculus

Aesculus is a genus of deciduous trees and shrubs in the soapberry family Sapindaceae. It contains about 15–20 species, commonly known as horse chestnuts or buckeyes. Native to temperate regions of Europe, western Asia, and North America, the genus is widely cultivated as an ornamental group for its showy flowers and large, palmately compound leaves.

Plants in the genus have palmate leaves with five to seven leaflets. In spring they bear panicles of white to pale pink flowers. The fruit is a spiny capsule that usually contains one or two large seeds, known as conkers or buckeyes. The seeds are toxic if eaten in quantity, containing compounds such as aesculin and other glycosides, so handling and consumption should be cautious.

Notable species include Aesculus hippocastanum (European horse chestnut), Aesculus glabra (Ohio buckeye), Aesculus flava (yellow buckeye), and Aesculus pavia (red buckeye). A. hippocastanum is native to Europe and western Asia, while several North American species are native to eastern North America. The genus is widely planted as an ornamental tree in urban landscapes, parks, and campuses, and individual species may be appreciated for their spring flowers and autumn foliage.

Ecology and cultivation: Aesculus species prefer fertile, well-drained soil and full sun to partial shade. They can be susceptible to pests and diseases such as leaf miners and cankers, and some cultivars may require care to maintain form in urban settings. The common name buckeye refers to the appearance of the seeds, which has led to cultural associations, particularly in the United States.