The total masses of the four populations with inhomogeneities measured by φ_σ. The collision velocities are v₀ = 10   m   s^-1 (top) and v₀ = 12.5   m   s^-1 (bottom). The masses of the largest fragment m₁, of the second largest fragment m₂, of the power-law population m_pw, and of the sub-resolution population m_sr are stacked and normalised by the total mass of the system m_tot. In both cases, m₁ and m₂ decrease with increasing φ_σ. Conversely, m_pw and m_sr increase. For the homogeneous case (φ_σ = 0), sticking is found for the low velocity collision, whereas for v₀ = 12.5   m   s^-1m₂ ≠ 0 and m_pw ≠ 0, which indicates fragmentation.