Prevalence of alien weed Parthenium hysterophorus L. in grazing and wastelands of district Attock, Pakistan.

Surveys of waste and grazing lands from 9localities of the district Attockwere undertaken during March-April, 2009 to study the distribution of alien weed parthenium ( Parthenium hysterophorusL.) in comparison with the other weed speciesof the area. A total of58weed species belonging to 2 5angiospermic families, were found growing in the studied area.Fourteen weed species, including parthenium were foundto be growingin all the 9surveyed sites exhibiting 100% prevalence.Parthenium was found to be the most frequently occurring species in the area with absolute frequency (AF) of 60% and relative frequency (RF) of 4.52%. Parthenium was also the most densely populated weed in the area exhibitingan absolute density (AD) of 19.4 and relative density (RD) of 0.67%. The second most frequently occurring and densely populated weed in the area was Achyranthes asperL..The present study concludes that pa rthenium has become one of the major weeds in district Attock. There is an urgent need to take some appropriate measures to stop its further spread in the area.