Abstract: The cotton harvester includes a cotton picker housing having at least one plant lifter defining a plant row channel extending back into the housing to a plant compressor sheet. A picker rotor is mounted in the cotton picker housing adjacent to the plant row channel and traverse to the plant compressor sheet. A doffer in the housing near the picker rotor removes picked cotton from the picker rotor and moves the picked cotton to an outlet at the rear of the cotton picker housing. A power unit includes an internal combustion engine mounted on the housing including a rotatable output selectably connectable in rotatably driving relation to the picker rotor and the doffer for imparting rotation thereto. The power unit can also selectably drive at least one wheel of the harvester for moving it over the ground at a speed corresponding to a rotational speed of the picker rotor.