In the years 2007-2009 the differentiation of flora on the area of balks of different length was assessed. The studies of flora were carried out in the area of 7772 ha of Ińsko Lakeland in Poland. For the detailed studies 72 balks were chosen, formed from roadsides and divided into two groups according to the length. Topographic maps in the scale 1:10 000 were used for the assessment of earlier functions of the studied objects. It was shown that in the areas of an arable surface characteristic of average farms as regards their size in the European Union, the size of arable land and the length of balks related with it had an influence on phytodiversity. Despite the fact that the number of phytocoenoses was larger on shorter balks, their specific poverty did not affect biodiversity significantly. The presence of a large number of melliferous species influenced not only phytodiversity of balks, but it also resulted in the improvement of nutritive conditions, among others, for bees. A larger number of plant species on long balks, including also melliferous and therapeutic species, proves correct management of the production space in a long time period.