Technical Abstract: One of the greatest advances in plant science has been the designation and study of model plants. Although model systems have benefited the weed science community by providing a greater understanding of plant physiology and genetics, the scientific gains have often precluded the analysis of traits that are of specific interest to the weed science community. Significant information and tools now exist to qualify leafy spurge as a model perennial weed. Leafy spurge is an aggressive perennial weed that infests uncultivated land throughout the Northern Great Plains. Like many perennials, it produces and maintains underground adventitious buds that re-grow each spring. These buds display para-, eco-, and endo-dormancy, and are relatively easy to grow, collect, and study. The genome size of leafy spurge is estimated to be only about 3 times larger than Arabidopsis. Clonal propagation of leafy spurge in the greenhouse is routine, and transformation protocols are being developed. Physiological and molecular studies have identified many signals and responses associated with dormancy control in leafy spurge. Numerous cDNA libraries are available for leafy spurge including: a two-hybrid library developed from 3 day induced growing buds; a normalized whole plant library that includes tissue from greenhouse and field grown plants, and plants stressed by disease, insect predation, and environmental extremes; and subtracted libraries developed from growing and dormant buds. In addition, a high quality genomic library has been constructed for leafy spurge. Development of an EST database containing more than 23,000 unique singletons and contigs is now available from the whole plant normalized library. There are current plans to produce cDNA microarrays containing all unique sequences from leafy spurge plus more than 9,000 unique sequences from cassava (a closely related species). Initial cDNA Microarrays, developed from a small EST-database derived from the 3 day induced growing bud library, were successfully used to identify differentially expressed genes in buds during various stages of dormancy and growth.