Broccoli is a stout, thick stemmed edible green plant in the Brassicaceae family, which also includes cabbage. The part we eat is actually the buds of the broccoli flower. If left unharvested, the broccoli head will open into small greenish-yellow flowers. Although most broccolis are green, there are also some delicious and beautiful purple varieties. Broccoli is a biennial, but it can go to seed the first year, if planted in early spring.