Conopodium majus

About

Conopodium majus is a perennial herbaceous flowering plant in the celery family, Apiaceae. Its underground part resembles a chestnut and is sometimes eaten as a wild or cultivated root vegetable. The plant has many English names variously including kippernut, cipernut, arnut, jarnut, hawknut, earth chestnut, groundnut, and earthnut. From its popularity with pigs come the names pignut, hognut, and more indirectly Saint Anthony's nut, for Anthony the Great or Anthony of Padua, both patron saints of swineherds.

Summary from Wikipedia