Cabbage (Brassica oleracea or variants) is a leafy green
biennial, grown as an annual vegetable for its dense-leaved
heads. Closely related to other cole crops, such as broccoli,
cauliflower and brussels sprouts, it descends from B. oleracea
var. oleracea, a wild field cabbage. Cabbage heads generally
range from 1 to 8 pounds (0.5 to 4 kg), and can be green, purple
and white. Smooth-leafed firm-headed green cabbages are the most
common, with smooth-leafed red and crinkle-leafed savoy cabbages
of both colors seen more rarely. It is difficult to trace the
exact history of cabbage, but it was most likely domesticated
somewhere in Europe before 1000 BC. By the Middle Ages it was a
prominent part of European cuisine, although savoys were not
developed until the 16th century. Cabbage heads are generally
picked during the first year of the plants' life cycles, but
those intended for seed are allowed to grow a second year, and
must be kept separated from other cole crops to prevent cross
pollination. Cabbage is prone