A sickle drive (62A, 62B) for a plant cutting machine having a first sickle knife assembly supported for side to side reciprocating movement along a forward end of a floor of the machine, a knife arm connected in driving relation to the sickle knife assembly, and a rotary power source for driving the knife arm, the drive (62A, 62B) being disposed at least largely in a generally flat cavity in or below the floor and including a disk shaped first input element supported for rotation about a generally upstanding first rotational axis and connected in rotationally driven relation to the rotary power source, a first eccentric element connected to the first input element for rotation eccentrically about the first rotational axis, a first drive arm disposed in the cavity in generally horizontally coextensive relation with the first input element and having a first end connected to the eccentric element for rotation therewith eccentrically about the first rotational axis, the first drive arm having a second end pivotally connecting to a first pivot element disposed beside the first input element, the first pivot element being supported for rotation about a generally upstanding first pivotal axis and having a first pivot arm extending eccentrically relative to the pivotal axis to the pivotal connection to the drive arm, such that the eccentric rotation of the first eccentric element will cause the first drive arm to reciprocatingly pivot the first pivot element about the first pivotal axis along a limited path, and the first pivot element being configured for connecting to the knife arm such that the pivotal movement of the first pivot element will reciprocatingly move the first sickle knife assembly sidewardly relative to the machine, the drive (62A, 62B) including a disk shaped second input element supported beside the first input element for rotation about a generally upstanding second rotational axis and connected in rotationally driven relation to the rotary power source, a second eccentric element connected to the second input element for rotation eccentrically about the second rotational axis, a second drive arm disposed in the cavity in generally horizontally coextensive relation with the second input element and having a first end connected to the second eccentric element for rotation therewith eccentrically about the second rotational axis, the second drive arm having a second end pivotally connecting to a second pivot element disposed beside the second input element, the second pivot element being supported for rotation about a generally upstanding second pivotal axis and having a second pivot arm extending eccentrically relative to the second pivotal axis to the pivotal connection to the second drive arm, such that the eccentric rotation of the second eccentric element will cause the second drive arm to reciprocatingly pivot the second pivot element about the second pivotal axis along a limited path (136, 136A), and the second pivot element being configured for connecting to a second knife arm of the machine such that the pivotal movement of the second pivot element will reciprocatingly move a second sickle knife assembly of the machine sidewardly relative to the machine, characterized in that, the first input element and the second input element are connected together for joint rotation in opposite rotational directions, for reciprocatingly moving the first and second sickle knife assemblies sidewardly simultaneously in opposite directions, and in that the sickle drive (62A, 62B) further comprises a rotatable power source connected in rotatably driving relation to one of the first input element and the second input element.