The pilot and passenger departed for a local flight that was to remain in the airport traffic pattern of the departure airport. The pilot stated that he climbed to pattern altitude and flew a normal downwind leg for runway 25. The pilot stated that when he turned onto the final leg of the approach, he was blinded by the sun and recognized that he was too low. He attempted a climb and felt the wing hit something, which was a tree about 100 feet from the runway approach end. He reentered the traffic pattern and landed on runway 25 without further incident. Damage to the airplane included a 2-3 inch dent in the left wing leading edge with damage to the underlying ribs. The pilot and passenger were uninjured. The damage was discovered by a Federal Aviation Administration inspector during an inspection of the repair facility where the airplane was undergoing repair.