The root growth rate of alloplasmic rye (Secale cerealeL. nucleus andTriticum durumDesf. cytoplasm) is approximately 30% lower than that of non-alloplasmic rye. To summarise, we can make the following concluding observations: i) Both normal and alloplasmic rye fit equilibrium kinetics; ii) the mitotic and phase indices are similar in both materials, and are also constant for roots with a length of between 10 to 60 mm.; iii) the cycle duration is sligtly shorter in CAL than in Elbon; iv) the final length of CAL cell is also slightly shorter than the Elbon ones; and v) the number of meristematic cells is notably lower in Cal than in Elbon. This might be the main cause for the lesser growth of alloplasmic plants.