On August 26, 2001, at 1720 central daylight time, a Schleicher ASK-21, glider, N121FL, registered to a private owner, collided with high vegetation while maneuvering for an emergency landing near Eagleville, Tennessee. The instructional flight was operated by Eagleville Sailplane Inc., under the provisions of Title 14 CFR Part 91 with no flight plan filed. Visual weather conditions prevailed at the time of the accident. The glider sustained substantial damage, and the air transport pilot was not injured. The flight departed Pickett Gliderport in Eagleville, Tennessee, at 1635. The pilot reported that after takeoff he flew to an area of thermal activity. Upon completing several minutes of upper airwork, the pilot elected to return to the departure airport. While en route to the departure airport, the pilot realized that he had entered an area where he was unable to maintain altitude and thermal activity was lost. The pilot selected a nearby bean field for an emergency landing. According to the pilot, during the landing roll, the right wing collided with a tall plant and the glider ground looped. Examination of the glider at the accident site revealed structural damage to the fuselage aft section. No mechanical problem was reported by the pilot.