The invention relates to a rotary lawn mower cutting blade (110). The cutting blade (110) is arranged to rotate about a vertical axis of rotation (A) of a lawn mower (100). The cutting blade (110) includes a base portion (204), arranged to connect the cutting blade (110) to a rotating carrier member (108) attached to the lawn mower (100). The cutting blade (110) further includes a cutting portion (208) having at least one recess is formed in a peripheral edge of the cutting portion (208). The at least one recess define at least one concave cutting edge (210).
