Genus (Plantae): Aesculus

The genus Aesculus (/ˈɛskjʊləs/ or /ˈaɪskjʊləs/), with varieties called buckeye and horse chestnut, comprises 13–19 species of flowering plants in the soapberry and lychee family, Sapindaceae. They are trees and shrubs native to the temperate Northern Hemisphere, with six species native to North America and seven to thirteen species native to Eurasia. Also, several hybrids occur. Aesculus exhibits a classical Arcto-Tertiary distribution.

Carl Linnaeus named the genus Aesculus after the Roman name for an edible acorn. Common names for these trees include "buckeye" and "horse chestnut", though they are not in the same order as chestnut trees. Some are also called white chestnut or red chestnut. In Britain, they are sometimes called conker trees because of their link with the game of conkers, played with the seeds, also called conkers.

Reference: Wikipedia