Possible secular trajectories for the HD 74156 system seen in the (ω₁,e₁) plane for two different values of the initial mutual inclination, I₀ = 40° (top), and I₀ = 50° (bottom). We show the trajectories using the quadrupolar approximation, corresponding to the level curves of constant energy. Each one corresponds to an initial value of the argument of the periastron ω₁, ranging from 0° (black) to 90° (red) with a step of 10°. The dashed black curves correspond to the observed eccentricity of the planet, that is, it gives the initial condition for ω₁. All trajectories are compatible with the current knowledge for this system (Table 1).