Abstract: A rotary mower (42) suitable for mowing ground vegetation including a cutting system (76) having a cutting deck (105). Mounted beneath the cutting deck (105) is a plurality of rotatable cutting blades (16), wherein each cutting blade (16) comprises a central portion (60) and first and second spaced apart tip portions (62a, b), wherein each tip portion (62) comprises a leading edge (56 ) having a sharpened cutting surface (64) for cutting the vegetation, a trailing edge (58), and an extending surface or "sail" (70) generally extending from the tip portion (62), whereby the sail (70a) of the first tip portion (62a) is different from than the sail (70b) of the second tip portion (62b).