The pilot was returning from a cross-country flight in a tail wheel equipped airplane. He reported a slight headwind and a stable approach until flare, then a crosswind lifted the left wing and the aircraft began exiting the runway environment. Attempts to regain directional control with rudder, aileron, and power were ineffective resulting in a collision with trees. The pilot and passenger were uninjured. The pilot reported there were no preaccident mechanical malfunctions or anomalies that would have precluded normal operation.