Abstract: A rotatable blade assembly suitable for use on a rotary power lawn mower is provided having an elongated bar member adapted to rotate in a substantially horizontal plane within the housing of a rotary lawn mower to which is detachably secured at diametrically opposed ends thereof cutting blade elements having cutting edges formed at oppositely facing edges which can be secured to the bar member without the need for special tools for removing the blade assembly from the shaft of the mower motor.