The wing (10) having a negative dihedron for towing a load comprises a flexible canopy (12) which is defined between two lateral ends (14A, 14B) which are connected to each other, at the front, by a leading edge and, at the rear, by a trailing. The wing (10) includes rear lines (40A, 40B) which are connected to the suspension members (30A, 30B) which are arranged at the lateral ends (14A, 14B) of the wing, and in that the auxiliary maintenance means of the propulsive central region (16) comprise at least a front line which is connected by one end to the propulsive central region adjacent to the leading edge and which is capable of being connected to the load at the other end. The front lines comprise an assembly of shroud lines (90A, 90B) which are applied to the propulsive central region (16) at locations which are distributed over the length of the leading edge, at least one sliding shroud line (90A, 90B) being engaged in a sliding manner in a guide (92A, 92B) which is fixedly joined to the leading edge, the end of the sliding shroud line (90A, 90B) being fixedly joined to a rear line (40A, 40B).