  It is developed a microscopic description of superconductivity in
ferromagnetic materials with triplet pairing triggered by the exchange of
magnetic fluctuations. Instead widely used paramagnon model we work with
phenomenological spectrum of fluctuations in the orthorhombic ferromagnet with
strong magnetic anisotropy. Depending of the field orientation parallel or
perpendicular to the direction of spontaneous magnetization the effective
amplitude of pairing interaction proves to be decreasing or increasing function
of magnetic field that allows to explain the drastic difference in magnitudes
of upper critical field in these directions.
