As part of efforts to address fire problems in the wildland-urban interface, the cone calorimeteris being used to measure the relative flammability of different plant species. In the first twostudies, we tested plants used to landscape homes in California and an assortment of plantsfound in Colorado. Using the effective heat of combustion and the peak heat release rate, wefound significant differences between some plants. Current efforts include a study of therelative flammability of native and invasive plants of the northeastern United States. We needto continue our evaluation of the benefits and limitations of using the cone calorimeter tomeasure the relative flammability of different plant species.