The natural convection flows from the wall and free plumes above a horizontal heat line source in a non-Darcian porous medium are investigated. The non-Darcian convective, boundary viscous and inertia effects arc all considered. The results indicate that the non-Darcian effects decrease the peak velocities and increase the maximum temperatures, and thicken the temperature boundary layer. In addition, the wall plume has a lower peak velocity and a higher maximum temperature than the corresponding free plume. Moreover, solutions by using local similarity and local non-similarity methods overestimate the maximum temperature and peak velocity for both wall and free plume cases.