The Greengrass family traces its roots back to the 9th century, the oldest known patriarch being Alastor Greengrass. The modern Greengrass family is actually descended of the Finnish Virtanen family. In the early 20th century, the last remaining Greengrass family member, Circe Greengrass, married Samuel Virtanen who did something that shocked Wizarding society; he changed his last name to Greengrass in order to continue the family line.