Nuclei are dynamic structures that move through the mitotic cell cycle, are involved in differentiation, and divide and fuse during reproduction. The DNA contents of nuclei from different plants vary by 2500-fold. The design and structure of nuclei is, therefore, both flexible and versatile. Features relating to genome, chromosome, and maybe even gene localization during interphase are now emerging. At the chromosomal level, studies of scaffold associations and DNA sequence organization are indicating structures that impose nuclear architecture.