Small heads of bok choy with plump green stalks, the name used in most of the north. Usually stir-fried plain or with shiitake mushrooms, and sweeter after a winter frost. The word also names the rapeseed plant.
Literally 'oil vegetable', grown for the seeds that yield 菜籽油 (cooking oil). Luoping (Yunnan) and Wuyuan (Jiangxi) draw massive spring tourism for their golden 油菜花 fields.
usage
In northern markets and on menus, 油菜 is the small green-stalked bok choy that Shanghai people simply call 青菜. In the south the word more often means the rapeseed plant and its tender greens.