Also known as buckeye, the horse chestnut tree is a member of the Hippocastanaceae family, with large, showy pink or white flowers. Not to be confused with the edible Castanea chestnut, horse chestnut fruits are inedible and poisonous, but their seeds, leaves and bark have many valuable properties and have been used in traditional medicine for many years. In beauty, horse chestnut’s seed extract has many applications and is a good astringent and antioxidant, widely used in hair care and personal care products.