broccoli broccoli and lettuce brown colors colours food fresh green greens healthy lettuce textures variety vegetables veggies Denmark eat edible hungry Big Head cholesterol-lowering benefits salad vegetable brassica oleracea broccoflower broccoli-cauliflower cross cauliflower cauliflower cultivar cross-pollination cruciferous cultivar curd color curd colour flavor flavour green cauliflower green-headed inflorescence inflorescence meristems milder nutritious plants sweeter texture white cauliflower