The paper presents some elements of Melampyrum arvense biology in plant community in the region of the Chełm Hills. The research was conducted on the roadsides, where rich stations of Melampyrum arvense were found, as well as in the neighbouring fields, of cereals (winter wheat and rye). Phytosociological records by Braun-Blanquet method were done in 2006 and 2007 on the rendzina soil in three localities: Anusin, Bezek and Mogielnica. At the same time from each station 30 plants were chosen to determine the height of plants and the number of offshoots. The result of the research carried out in the roadsides and corn-field shows that Melampyrum arvense occurs in the rich floral phytocenosis. Melampyrum arvense finds better conditions for growth and development in the habitats of roadsides than in agrocenosis. Melampyrum arvense plants from roadsides were higher and had more shoots than plants from segetal phytocenosis. Presumably agricultural chemicalization does not favour Melampyrum arvense appearing in segetal phytocenosis, which results in the lack of its presence in cereal plants far from the roadsides. But some features such as purple and yellow, thick inflorescence, long period of flowering and growing in large concentration let us include Melampyrum arvense into the species group which besides increasing biodiversity of native flora, influence the colour of agricultural landscape.