Flowering plant (angiosperm) genomes are exceptional in their variability with respect to genome size,ploidy,chromosome number,gene content,and gene arrangement.Gene movement,although observed in some of the earliest plant genome comparisons,has been relatively underinvestigated.We present here-in a description of several interesting properties of plant gene and genome structure that are pertinent to the successful movement of a gene to a new location.These considerations lead us to propose a model that can explain the frequent success of plant gene mobility,namely that Small Insulated Genes Move Around (SIGMAR).The SIGMAR model is then compared with known processes for gene mobilization,and predictions of the SlGMAR model are formulated to encourage future experimentation.The overall results indicate that the frequent gene movement in angiosperm genomes is partly an outcome of the unusual properties of angiosperm genes,especially their small size and insulation from epigenetic silencing.