Broccoli is a stout, thick-stemmed plant in the Brassicaceae family, which also includes cabbage, kale, and Brussels sprouts. Large, blue-gray leaves are leathery and oblong, arranged around an upright trunk-like structure that supports a flowering head. The part we eat is actually the buds of the broccoli flower. If left unharvested, the broccoli head would open into small greenish-yellow flowers. Although most broccoli is green, there are also some delicious and beautiful purple varieties. Broccoli has a moderate growth rate. It is typically planted in the early to mid-spring for an early summer harvest.