On May 31, 2003, about 2030 central daylight time, a Cessna 172M, N9900V, collided with trees during takeoff from Montgomery County Field, Conroe, Texas. N9900V, Inc., was operating the airplane under the provisions of 14 CFR Part 191. The certified flight instructor (CFI) pilot and the student pilot sustained minor injuries; the airplane sustained substantial damage. The cross-country instructional flight was en route to West Houston Airport, Houston, Texas. Visual meteorological conditions prevailed, and no flight plan had been filed. The primary wreckage was at 30 degrees 21 minutes north latitude and 95 degrees 25 minutes west longitude. The CFI submitted a Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2). The CFI stated that they departed from the West Houston Airport about 1600. They made an intermediate stop for practice landings, and then flew to Montgomery Field. They refueled and completed flight planning for the return flight to West Houston. The CFI stated that it was hot, about 35 degrees Celsius (95 degrees Fahrenheit), and he had concerns about the airplane's takeoff performance. Therefore, he elected to execute the takeoff instead of letting the student do it. He heard the stall warning horn sound after rotation. He lowered the nose to try and gain airspeed in ground effect. However, the airplane stalled and banked left. He applied right aileron and full right rudder. The airplane continued to veer to the left of the runway. The CFI recognized the loss of control, and that the airplane was headed toward the trees. He pulled the power to idle and attempted to abort the takeoff. The airplane collided with trees while the airplane was still 40 feet above ground level (agl).