Wild B. oleracea is a tall biennial or perennial plant[3] that forms a stout rosette of large leaves in the first year.

The grayish-green leaves are fleshy and thick,[4] helping the plant store water and nutrients in difficult environments.

In its second year, a woody spike grows up to 1.5 metres (5 ft) tall, from which branch off stems with long clusters of yellow four-petaled flowers.

[5] A 2021 study suggests that Brassica cretica, native to the Eastern Mediterranean, particularly Greece and the Aegean Islands, was the closest living relative of cultivated B. oleracea, thus supporting the view that its cultivation originated in the Eastern Mediterranean region, with later admixture from other Brassica species.

[6] Genetic analysis of nine wild populations on the French Atlantic coast indicated their common feral origin, deriving from domesticated plants escaped from fields and gardens.

It has been bred into a wide range of cultivars, including cabbage, broccoli, cauliflower, brussels sprouts, collards, and kale, some of which are hardly recognizable as being members of the same genus, let alone species.

Researchers believe it has been cultivated for several thousand years, but its history as a domesticated plant is not clear before Greek and Roman times, when it was a well-established garden vegetable.

[16] Through artificial selection for various phenotype traits, the emergence of variations of the plant with drastic differences in appearance occurred over centuries.

[dubious – discuss] Bitter taste receptors in the TS2R family are also found in gut mucosal and pancreatic cells in humans and rodents.

[25] Three variants in the TAS2R38 gene – rs713598, rs1726866, and rs10246939 – are in high linkage disequilibrium in most populations and result in amino acid coding changes that lead to a range of bitter taste perception phenotypes.