FLORISTIC ANALYSIS OF THE WEED COMMUNITIES IN WHEAT AND CORN CROPS: A CASE STUDY IN WESTERN-CENTRAL ITALY

Since a large area of Italy is lacking of updated informations about weed flora, we carried out a field survey in wheat and corn crops in western-central Italy (Lazio), by phytosociological approach, to update data, making comparisons and diachronic observations&nbsp; with literature. Relev&eacute;s were carried out in 62 wheat crops, 50 corn ones. Totally 149 vascular units and 36 families were recorded; Poaceae and Asteraceae are prevailing. In wheat fields 113 units were observed: Dicots <em>s.l.</em> are 77,88% and Monocots 22,12%; in corn fields 78 units were observed. Floristic composition of relev&eacute;s is very variable. In both cultivations Therophytes, Mediterranean and wide distribution <em>taxa</em> dominate. Among wheat weeds one alien species was observed; greater (11%) was the occurrence of non-native <em>taxa</em> in corn crops. The comparison of the surveys in 1981 and in 2011-2012 showed the prevailing of Asteraceae, Fabaceae, Brassicaceae, Poaceae, even if in different percentages. A strong increase of Therophytes and Mediterraneaneans is detected. Wheat crops weed flora has a higher value than that in corn crops, because of species richness and mostly native <em>taxa</em> presence. The prevailing of Dicots, not resistent to herbicides, can be considered an indicator of good conservation status of agro-ecosystems