A plant that produced more than one kernel in many of its florets was isolated from breeding material. The condition was found to be transmitted in monogenic fashion as a recessive character. Transmission of the mutation through the egg cells appears to be normal, but transmission through the pollen is considerably lower. Expression of the pistilloid condition in recessive homozygotes appears to be modified by at least one further gene. Three types of pistilloidy were apparent, firstly, the production of additional pistils without the sacrifice of stamens, secondly, the production of 3–4 pistils but no stamens and, thirdly, the development of additional pistils at the expense of a corresponding number of stamens. The mutation is associated with chromosome arm 6BS and recombinationally may be located close to the centromere. A comparison of C-bands showed that chromosome arm 6BS of the mutant line B13, lacks a heterochroma- tic sub-satellite region which is present in‘Chinese Spring’. It is possible that a spontaneous interstitial deletion occurred at this position, resulting in the abnormality.