In the present contribution the anisotropic structure of the two-dimensional
linear Cosserat elasticity is investigated. The symmetry classes of this model
are derived and detailed in a synthetic way. Particular attention is paid to
specific features of Cosserat elasticity: sensitivity to non-centrosymmetry
and to chirality. These aspects are important for the application of this
continuum theory to the mechanical modelling of lattices and metamaterials.
In order to give a parameterisation to the Cosserat constitutive law, an
explicit harmonic decomposition of its constitutive tensors is provided. Finally,
using an algorithm introduced in a side paper, a minimal integrity basis,
which is the minimal set of polynomial invariants generating the algebra of
-invariant
polynomials, is reported.