Technical Abstract: The invasion of habitats by non-native organisms is considered, behind habitat destruction, the second largest threat to biodiversity worldwide. Consequently, control of invasive organisms is now an integral part of ecosystem stewardship. Effective control may require explicit characterization of the invasion at the family, species, and/or population levels. Tamarix is considered one of the worst plant invasions in the United States. A synopsis of molecular systematic advances at the family and species levels is presented, and the impact on the control of Tamarix is discussed. Also, a preliminary population-level analysis of T. ramosissima is performed using chloroplast DNA sequence data. This analysis investigates origins of invasive haplotypes and tests for the presence of cultivated haplotypes in the invasion. Advances in understanding invasions through molecular systematic and population-level studies will prove to be powerful tools in many control scenarios.