Presence of two associations belonging to Panico-Setarion alliance (order Polygono-Chenopodietalia) was observed in the root cultivations of the Siedlce city. The largest area of the city arable lands was covered by plots of association Echinochloo-Setarietum, differentiated internally into 3 variants (typical, with Matricaria maritima subsp. inodora and with Galinsoga parviflora). Variant with Matricaria was divided into two subvariants, different as to moisture conditions. Association Digitarietum ischaemi, occurring on the poorest habitats was noted very seldom in root cultivation of the Siedlce city, considering the diminish of its habitat acreage. The similar process is observed in the whole Poland. The vegetation described in the paper is characterized by a large flora biodiversity and large participation of ruderal species originating from surrounding communities.

19-31