High plants between GM and non-GM fields that physically limit pollen movement

A pollen barrier is intended to limit out-crossing of GM crops in adjacent conventional fields. Such a barrier may consist of plants tall enough to catch flying pollen, for example hedges or trees; similarly, such as in the case of a plot of GM maize, the barrier may be a surrounding strip of conventional maize, which not only catches pollen but produces conventional pollen that competes with the GM pollen.