Aesculus species have stout shoots with resinous, often sticky, buds, with opposite, palmately divided leaves, often very large—to 65 cm (26 in) across in the Japanese horse chestnut, A. turbinata.

Flowers are showy, insect- or bird-pollinated, with four or five petals fused into a lobed corolla tube, arranged in a panicle inflorescence.

[6][7][8] All parts of the buckeye or horse chestnut tree are moderately toxic, including the nut-like seeds.

The USDA notes that the toxicity is due to saponin aescin and glucoside aesculin, with alkaloids possibly contributing.

[11] Native Americans used to crush the seeds and the resulting mash was thrown into still or sluggish waterbodies to stun or kill fish.

The horse chestnut was not native to Britain and was only introduced from Europe in 1650 (on the estates of both Dawyck House and Stobo Castle).

In North America, several native American tribes, particularly in the western and central United States, such as Miwok, Pomo, Yokut, Maidu, historically used Buckeye trees (Aesculus spp.)

These tribes used crushed Buckeye nuts to release saponins into streams or shallow water, where the compounds would stun or kill the fish, allowing for easier capture.