Cauliflower (Brassica oleracea var. botrytis) is a cool-season brassica grown for its dense white head — a tight dome of thousands of arrested flower buds packed into a single edible "curd." Mild, faintly sweet and cabbage-like raw, it turns nutty and sulfurous when cooked and meltingly tender when roasted, and is the same species as cabbage, broccoli, kale and Brussels sprouts.