The legislation on the control of thistles and that on the management of verges yields a conflicting situation. The aim of this research is to make an evaluation of the degre to which thristles really form a problem in verges of roads and waterways of the Flemish community. This will be achieved through an extensive vegetation survey including an analysis of the ecological conditions (soils, management, neighbouring land use). Also an elaborated questionnaire will enable an assessment of the degre that thistles really form a problem to people. After data analysis education material will be developed.