Rhizomatousness is a key trait influencing both the perenniality and biomass partitioning of plants. Increased understanding of the genetic control of rhizome growth offers potential towards the creation of more sustainable grain, forage, and bioenergy cropping systems. It is also applicable to the advent of control methods for some of the world’s most problematic weeds, notably Johnsongrass [Sorghum halepense (L.) Pers]. The sorghum genus has become a model for the identification of genes controlling rhizomatousness and perenniality.  QTLs correlated with rhizome growth have previously been identified using populations derived from crosses between S. bicolor (L.) Moench. and S. propinquum (Kunth.) Hitchc. In this study we have used a population of F₄ NIL’s segregating for rhizomatousness to further refine a previously identified QTL region.  Results and implications will be discussed.