Ungnadia is a genus of flowering plants in the family Sapindaceae containing one species, Ungnadia speciosa, the Mexican buckeye, a shrub or small tree native to northern Mexico as well as Texas and southern New Mexico in the United States. The name honours David Baron von Ungnad (d. 1600), who first brought the horse chestnut to Vienna. It differs from the buckeyes in the related genus Aesculus in having alternate, pinnate leaves with 5-7 leaflets, but the flowers and nuts are similar. Another similar related genus is the soapberry (genus Sapindus).