Brassica oleracea
Collard refers to certain loose-leafed cultivars of "Brassica oleracea", the same species as many common vegetables, including cabbage (Capitata Group) and broccoli (Italica Group). Collard is a member of the Viridis Group of "Brassica oleracea". American collard cultivars are more correctly placed in the Viridis cultivar group due to a high genetic similarity with cabbage, although older publications often include them within the Acephala Group (kale). The name "collard" comes from the word "colewort" (a medieval term for non-heading brassica crops).