A surgical stapler has a tool assembly including an anvil and a staple cartridge having a series of staples which are supported and configured to be rotatably ejected from the staple cartridge into the anvil to suture tissue. In embodiments, the surgical stapler includes a cartridge that supports a plurality of rotatable pushers. Each pusher supports a curved, substantially U-shaped staple having a single tissue penetrating distal leg portion and a proximal leg portion. The pusher is rotatable to drive the distal leg portion into an anvil to deform the staple into a substantially D-shaped configuration.