The book is the most complete summary summarizing numerous studies of weeds carried out in the USSR over the past 50 years. It describes the biological features of 1000 species of weeds, their distribution in 6 regions and 46 floristic regions of the USSR, as well as the abundance and occurrence in crops. For 80 species of widely distributed and often abundant weeds in crops, detailed information is provided about their biology and the peculiarities of combating them. Keys are given to identify families, genera and species of weeds. There are 40 tables showing significant details of about 400 plant species.