Nongyrotropic particle populations can bring about linear mode coupling in homogeneous media among the three eigenmodes of parallel propagation in gyrotropic magnetoplasmas. These interactions stimulate, in general, wave activity tht does not occur in corresponding (random gyrophase) gyrotropic ambients. Solutions of the dispersion equation illustrate that simple introduction of gyrophase organization can (i) excite electrostatic (and electromagnetic) perturbations in media whose free energy sources are solely electromagnetic, and (ii) drive hybrid (both electrostatic and electromagnetic) wave growth in thoroughly stable Maxwellian plasmas. ¿ American Geophysical Union 1992