The term 'Member of the Mustard Family' refers to three edible plants: Cress (5 letters), ARUGULA (7 letters), and CAULIFLOWER (11 letters). Cress is a leafy green vegetable that is often used in salads. ARUGULA is a peppery-tasting salad green that is popular in Mediterranean cuisine. CAULIFLOWER is a cruciferous vegetable that can be eaten raw or cooked. All three of these vegetables are members of the mustard family, which is a large group of plants that includes many edible species.