An isolated nucleic acid obtainable from the VRN2 locus of a plant, which nucleic acid encodes a polypeptide which is capable of affecting one or more physical characteristics of a plant into which the nucleic acid is introduced, the physical characteristics being selected from vernalization response, flowering time, leaf size, and/or shape or shade avoidance response; alleles, fragment and derivatives thereof; polypeptides encoded by such nucleic acids; antibodies to such peptides.