Principal Component Analyses were made of data denoting aspects of reproductive and vegetative vigour in three progenies of strawberries that were segregating for autumn-fruiting and summer-fruiting genotypes; they gave a first vector which describes the negative association between reproductive and vegetative vigour and another which describes vegetative vigour that is independent of reproductive vigour. The analyses were therefore useful for identifying vegetatively vigorous autumn-fruiting types. For each family, the frequency of plants as designated by their weighting for their first vector followed a double normal and not a normal distribution: this supports the idea that there are two distinct but variable types of response to photoperiod-temperature factors rather than one continuum of response, and this is consistent with the idea that major genes determine the type of response.