The invention relates to 2-benzoylcyclohexane-1,3-diones of the formula I where R1, R2 are hydrogen, nitro, halogen, cyano, thiocyanato, alkyl, haloalkyl, alkoxyalkyl, alkenyl, alkynyl, —OR5, —OCOR6, —OSO2R6, —SH, —S(O)nR7, —SO2OR5, —SO2NR5R8, —NR8SO2R6 or —NR8COR6; R3 is hydrogen, alkyl, haloalkyl, alkenyl or alkynyl; R4 is hydrogen, unsubstituted or substituted alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, —COR9, —CO2R9, —COSR9 or —CONR8R9; X is oxygen or sulfur; Z is oxygen or NR8; m is 0 or 1; n is 0, 1 or 2; R5 is hydrogen, alkyl, haloalkyl, alkoxyalkyl, alkenyl or alkynyl; R6 is alkyl or haloalkyl; R7 is alkyl, haloalkyl, alkoxyalkyl, alkenyl or alkynyl; R8 is hydrogen or alkyl; R9 is alkyl, alkenyl, alkynyl, phenyl or benzyl; R10 is alkyl, haloalkyl, alkenyl or alkynyl; Q is an unsubstituted or substituted cyclohexane-1,3-dione ring which is linked in the 2-position; where m is 1 if R3 is hydrogen; and the agriculturally useful salts thereof; processes and intermediates for the preparation of the compounds of the formula I; compositions comprising them; and the use of these derivatives or compositions comprising them for controlling undesired plants.