Abstract: A rotary lawn mower specially adapted for selectively mulching and/or discharging grass clippings. The preferred embodiment comprises a lawn mower having a generally conventional cutting deck, with an integrated discharge chute/mulching plug hingedly secured to the deck adjacent the discharge opening. The integrated discharge chute/mulching plug is selectively movable between a plurality of positions, including a mulch position and a discharge position. In the mulch position, the inner wall of the plug member extends within the discharge chute to establish a generally continuous inner wall within the cutting chamber for improved mulching performance. The mower further includes an improved cutting blade, having a pair of raised rib sections intermediate the cutting edges and the central hub, the raised ribs being operative to create an additional upward air flow component to improve circulation during both mulching and discharging.