  We discuss a model of quantum photosynthesis with degeneracy in the
light-harvesting system. We consider interaction of excitons in chromophores
with light and phonons (vibrations of environment). These interactions have
dipole form but are different (are related to non-parallel vectors of "bright"
states). We show that this leads to excitation of non-decaying "dark" states.
We discuss relation of this model to the known from spectroscopical experiments
phenomenon of existence of photonic echo in quantum photosynthesis.
