INDIVIDUAL FLOWERING TIME IN A GOLDENROD (SOLIDAGO CANADENSIS): FIELD EXPERIMENT SHOWS GENOTYPE MORE IMPORTANT THAN ENVIRONMENT

Individual plants of an old field population of the clonal perennial goldenrod, Solidago canadensis L. are consistent in rank order of flowering time over years. In order to analyze whether this consistency is due more to environmental variations among microsites of individual clones or due to genetic variation among clones, similar‐sized sections of rhizomes were transplanted to an experimental garden in a randomized block design with five replicates per clone. Three years later we examined the transplants and the original plants for their flowering phenology. In the experimental garden there was an unexpected soil moisture gradient across blocks, with associated gradients in height of goldenrods and height of surrounding vegetation. No gradient was significantly correlated with the flowering time of the transplants. That is, the time of flowering of transplants was consistent among replicates of individual clones across the soil moisture gradient and regardless of the size of the transplants themselves, or the height of surrounding vegetation. Further, the flowering times of the transplants were significantly positively correlated with the flowering times of the original plants in the same year. We conclude that the differences in flowering time among clones within a goldenrod population is largely determined by genetic variation, rather than by environmental factors.