Classi®cation of Italian Xanthium strumarium complex based on biological traits, electrophoretic analysis and response to maize interference

Xanthium strumarium complex was studied taking plant seeds from 16 diverse locations in Italy. Plant morphophysiological traits were noted and electrophoretical analysis of seed reserve proteins was carried out from individual plants grown at the same site, in the presence and absence of competition from maize. Signi®cant correlations between diverse plant phenological traits, the geographical origin of the seeds and the seed protein electrophoretic patterns were found. A high correlation between seed reserve proteins and the genetic structure of this weed was also detected. Maize competition increased Xanthium stem growth and decreased bur production and number of branches. Xanthium plant populations could be classi®ed according to the morphological characters evaluated in three groups closely related to their geographical original area and latitude (northern, central and southern Italy), each showing precise morphological traits of Xanthium italicum, X. strumarium and X. orientale respectively. Electrophoresis supported the classi®cation of these three morphological groups.