Brassica rapa L. (syn. Brassica campestris L.) is a plant consisting of various widely cultivated subspecies including the turnip (a root vegetable); the mizuna, napa cabbage, and cime di rapa (leaf vegetables); and turnip rape (Brassica rapa subsp. oleifera, an oilseed which has many common names, including [annual] turnip rape, canola, field mustard, bird rape, and colza). The oilseed is sometimes confused with rapeseed oil, which however comes from a different Brassica species.

In the 18th century the turnip and the oilseed-producing variants were seen as being different species by Carolus Linnaeus who named them B. rapa and B. campestris. 20th-century taxonomists found that the plants were cross fertile and thus belonged to the same species. Since the turnip had been named first by Linnaeus, the name Brassica rapa was adopted.

The oilseeds known as canola are sometimes particular varieties of Brassica rapa (termed Polish Canola) but mostly related species Brassica napus and Brassica juncea.