Broccoli is in the cabbage family species Brassica oleracea, and is classified in the Italica cultivar group. Broccoli’s large flower heads are usually green and arranged in a tree-like structure on branches that typically sprout from a thick, edible stalk. The mass of flower heads is surrounded by leaves. Broccoli most closely resembles cauliflower, which is another cultivar group of the same species.
There are 3 commonly grown types of broccoli:
1. The most familiar is Calabrese broccoli – often referred to simply as "broccoli" – named after Calabria in Italy. It has large 4 to 8 inch green heads and thick stalks. It is a cool-season crop; thus, most varieties are planted and harvested ahead of hot summer weather. Broccoli grows best when exposed to an average daily temperature between 64° and 73° F. Broccoli should be harvested before the flowers on the head bloom bright yellow.
2. Sprouting broccoli has a larger number of “heads” with many thin stalks.
3. Purple cauliflower is a type of broccoli usually sold in southern Italy, Spain, and the United Kingdom. It has a head shaped like cauliflower, but consisting of tiny flower buds. It sometimes, but not always, has a purple cast to the tips of the flower buds.
Broccoli is usually boiled or steamed but may be eaten raw and has become popular as a raw vegetable in hors d'oeuvre trays. It is high in vitamin C and dietary fiber. Broccoli also contains multiple nutrients with potent anti-cancer properties; however, the health benefits of broccoli are greatly reduced when the vegetable is boiled. Other preparation methods such as steaming, microwaving, and stir-frying have no significant adverse effect on the nutritional compounds.
Other cultivar groups of Brassica oleracea in addition to broccoli and cabbage include kale, cauliflower, collard greens, kohlrabi, Brussels sprouts and Chinese broccoli. Broccoli Raab – actually a type of turnip (Brassica rapa) – forms heads similar to broccoli, but smaller.