Collard is a group of loose-leafed cultivars of Brassica oleracea, the same species as many common vegetables including cabbage and broccoli. Part of the Acephala (kale) cultivar group, it is also classified as the variety B. oleracea var. viridis.

Brassica oleracea is a plant species from family Brassicaceae that includes many common cultivars used as vegetables, such as cabbage, broccoli, cauliflower, kale, Brussels sprouts, collard greens, Savoy cabbage, kohlrabi, and gai lan.