The oil made from the seed is sometimes also called canola or colza, which is one reason why it is sometimes confused with rapeseed oil, but this comes from a different Brassica species (Brassica napus). The oilseeds known as canola are sometimes particular varieties of Brassica rapa (termed Polish Canola) but usually the related species Brassica napus (rapeseed) and Brassica juncea (mustard greens and mizuna).
Researchers at the University of Wisconsin–Madison have selectively bred one subspecies of B. rapa to have an extremely short life cycle for use as a model organism in education and experiment. This variety is known by the trademarked name "Wisconsin Fast Plants."
In the 18th century the turnip and the oilseed-producing variants were seen as being different species by Carl 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.
Many butterflies, including the small white, pollinate the B. rapa flowers.