We report the results of measuring Mueller matrices for three groups of leaf samples of common barley (Hordeum vulgare): Chlorina mutant, Chlorina etiolated mutant and Cesaer varieties. The repeatability of the measurement results of Mueller matrices of such a complex and highly depolarising object as a plant leaf is demonstrated. It is shown that the barley leaves of these three groups can be reliably identified both at forward scattering and backward scattering modes; the best results are obtained in the case of forward scattering. In both cases, the most informative matrix elements are identified. It is also shown that at backward scattering mode linear dichroism comes out, the magnitude of which increases with decreasing observation angle.