Abstract: An attachment for the lower end of a vertical drive-shaft of a wheel-mounted power mower of the rotary lawn mower type comprises a balanced assembly of centrally-bored shaft-engaging hub together with a plurality of equi-distantly spaced radially extending arms each of which carries a boss or lateral enlargement adjacent its outer end for receiving a quickly and easily replaceable flexible cutting line which projects freely therefrom in the general direction of the arm by which it is carried. The lower end of the vertical drive-shaft of the prime mover of the rotary mower, which ordinarily receives the mid-section of a rigid metallic cutting blade that is sharpened adjacent each of its ends, is attached to the hub of the rotary assembly of the invention, suitable adapter means being provided for accommodating driveshafts of different sizes.