Ubiquitous in the fields around Boston are crops of brassicas. Although differing in appearance cabbage, kale, broccoli, cauliflower and Brussels sprouts are all the same species. Cabbage is an important commercial crop and does well in the fenland soils. There are over 400 varieties of cabbage grown commercially. Cabbage is an exceptionally healthy food with an outstanding nutrient profile. The first round-headed cabbages appeared in England in the 14th century, and illustrations of cabbage harvesting can be seen in medieval manuscripts.