Not necessarily a plant without roots but one that can move from place to place. And not necessarily quickly.
Alternate name: Unrooted Plants
The first video game about Mobile Plants was released on December 17, 1988.
The plant must be able to move in some way on its own initiative. A minimal level of intelligence is assumed. Seed dispersal methods generally do not count. This includes seeds or parts of the plant that fly, are wind blown, attach to animals, roll down hills, or moved by fire.