Radar's potential as a sensor for surveys of natural and cultivated vegetation has recently been demonstrated in a preliminary way. Its combination of fine resolution from long distances with a virtual independence of weather and time of day makes radar particularly attractive for wide area surveys that must be performed quickly. Aircraft radar can effectively image a much wider swath of territory than other aircraft-borne sensors. This advantage, however, does not carry over into spacecraft radar, where the swath possible with optical sensors is much more than it is at aircraft altitudes. Radars with characteristics suitable for vegetation surveys have been developed for military reconnaissance in the past two decades. Because most of the images produced in the past by these radars have not been available to the scientific community, their potential for vegetation surveys is not recognized widely. Recently, however, many such images have been released and a few research programs have begun to document the potential of radar for vegetation studies. The kind of radar that will undoubtedly receive most application in plant geography (and perhaps even ecology) studies is side-looking airborne radar (SLAR). Such radar produces a continuous-strip image that looks much like a continuous strip photograph taken from a very high altitude. Unlike the photograph, however, the area imaged is not beneath the aircraft, but rather extends from a short distance out to the