A crucifer is any plant of the family Brassicaceae (formerly Cruciferae), having a
corolla of four
petals arranged like a cross and a
botanical fruit called a siliqua.
The family includes the brassicas, radish and cress.
The brassicas (i.e. plants in the Brassica genus) include cabbage, broccoli, cauliflower, kale, Brussels sprouts, turnips, and mustard.