Acetolysed and non-acetolysed pollen grains were examined by means of light and scanning electron microscopy. A short description of the pollen morphology of the parent speciesLinaria vulgarisandL. repensis presented. The frequency distribution of theP, EandP/Evalues of these species is shown in comparison with corresponding measurements of pollen grains from induced F1and F2individuals. The “species values” ofP, EandP/Ehave an expected normal distribution with short amplitudes. However, plants from the first filial generation of reciprocal crosses have as a rule extreme values widely separated and a bimodal distribution curve of theEvalues. A new method of wax-mounting of spores or similar objects on a specimen stub for SEM preparation is presented.