Common types of brassica used for food include cabbage, cauliflower, broccoli, Brussel sprouts, and some types of seeds. The genus is remarkable for containing more important agricultural and horticultural crops than any other genus. It also includes a number of weeds, both wild taxa and escapees from cultivation. It includes over 30 wild species and hybrids, and numerous additional cultivars and hybrids of cultivated origin. Most are annuals or biennials, but some are small shrubs. Due to their agricultural importance, Brassica plants have been the subject of much scientific interest. Six particularly important species (Brassica carinata, B. juncea, B. oleracea, B. napus, B. nigra and B. rapa) are derived by combining the chromosomes from three earlier species, as described by the Triangle of U theory.
The genus is native in the wild in western Europe, the Mediterranean and temperate regions of Asia. In addition to the cultivated species, which are grown worldwide, many of the wild species grow as weeds, especially in North America, South America, and Australia.
A dislike for cabbage, broccoli et.al. can be due to the Brassica species containing a chemical similar to phenylthiocarbamide (PTC), a chemical which is either bitter or tasteless depending on one's genetic makeup.