The pilot in the low-wing airplane reported that, while in the traffic pattern at the non-towered airport, he made continuous reports on the common traffic advisory frequency (CTAF). He added that, on final, he observed a high-wing airplane positioned adjacent to the runway he was approaching. On short final, "the runway was clear" and he heard no radio transmissions. The low-wing airplane impacted the high-wing airplane on the runway. The low-wing airplane yawed right, the high-wing airplane became visible, and the low-wing airplane came to rest nose down in front of the right wing of the high-wing airplane. The pilot receiving instruction in the high-wing airplane reported that, after performing a run-up, she and the flight instructor taxied to and held short of the departure runway. She added that, during the taxi, she and the instructor did not hear radio transmissions on CTAF from other aircraft in the traffic pattern. Before departure, they visually cleared final and base and reported on the CTAF their departure intentions. They lined up on the runway for a short field takeoff, held the brakes, and applied full power. She released the brakes and about 3 to 5 seconds into the takeoff roll, they heard a loud noise and the airplane was pushed left. The high-wing airplane came to rest with the low-wing airplane "dangling off the right side" of the high-wing airplane. The low-wing airplane sustained substantial damage to the left wing. The high-wing airplane sustained substantial damage to the right wing and empennage. Two eyewitnesses in the same airplane reported that while taxiing, they heard the high-wing airplane make a radio transmission that they were "taking the runway" and departing. They observed the high-wing airplane lined up on the runway but did not see any aircraft on base or final. Several moments later, they looked back and saw the high-wing airplane still on the runway, and also a low-wing airplane on final. One of the witnesses made a call on the "unicom" frequency warning the low-wing airplane that another airplane was on the runway but heard no response. He made another call to the low-wing airplane to perform a go around, and then they observed the low-wing airplane land on top of the high-wing airplane. The pilots of the low-wing and high-wing airplanes reported that there were no preaccident mechanical failures or malfunctions with the respective airplanes that would have precluded normal operation.