Thlaspi is a genus of plants in the family Brassicaceae. It is commonly known as pennycress or pursewort. The word Thlaspi has Greek origins, which means 'a small brass coin.' The plant is characterized by its small white flowers and round flat seed pods. Synonyms for Thlaspi include Arabis, Dentaria, Erophila, and Sisymbrium. Arabis and Dentaria are synonyms for the genus because of their similar seed pods. Erophila and Sisymbrium are synonyms because of their similar small white flowers. These synonyms are important for understanding the relationships between plant species and their adaptations to different environmental conditions.