The working-up of the huge amount of mown grass is a big problem in management of road verges in Belgium. A biological approach to reduce this cost could be given by the use of half-parasites that counteract the production of biomass of the vegetation. The first part of this project consists of a selection of potenital inte- resting species. A comparison is being made of natural sites and road verge vegetation. Seed production will be monitored. In the second part, the concerned species will be sown in road verges with divergent conditions (that could be interesting) and their response monitored. An answer will be searched to the following questions: How behave the most promessing species under field conditions ans what is the amount of biomass reduction in road verges? How do they react on mowing with removal of the hay? How is seed production? What factors influence seed production and the behavior in road verges? .....