Abstract It is argued in this paper that there are three distinctive physical situations in which the continuum descriptions of crystal plasticity are conceptually different. They are determined by the properties of the random field of dislocation density. One of the cases corresponds to conventional plasticity theory. In this case the system energy possesses the energy density, and a formula for energy density of the dislocation microstructure is derived. The phenomenology of the energy of microstructure is briefly discussed.