Abstract: A forage harvester row crop header having a mobile frame, at least one fore-and-aft extending row crop unit mounted on the frame and including an elongated passageway for receiving a row of crop as the header advances forwardly over a field of crop planted in spaced apart rows is provided with an improved severing mechanism for severing the crop within the passageway and which further insures the severance of grass-like materials within the crop row. The improved severing mechanism includes upper and lower rotary severing discs and a lower rotary guide disc. The upper and lower rotary severing discs are disposed on opposite sides of the elongated passageway and overlap within the passageway in defining a severing zone for severance of crop material. The lower rotary guide disc is mounted to and below the upper severing disc. Upon operation, the guide disc engages grass-like materials within the row crop and orients the same into the severing zone resulting in severance thereof.