A Brassica oleracea cultivar, gai lan is in the group alboglabra (from Latin albus "white" and glabrus "hairless").

When gone to flower, its white blossoms resemble that of its cousin Matthiola incana or hoary stock.

Gai lan is harvested around 60–70 days after sowing, just before the flowers start to bloom.

The "baby" version is cultivated through crowding of seedings and generous fertilization; they resemble Brussels sprouts although they have looser folds.

[6] The stems and leaves of gai lan are eaten widely in Chinese cuisine; common preparations include gai lan stir-fried with ginger and garlic, and boiled or steamed and served with oyster sauce.