Several woody and herbaceous energy crop species have been selected as high-potential candidates for supplying biomass feedstocks. Successful methods for their establishment and maintenance have been developed. Recommended species vary as a function of region of the country and soil type. Yields are equally variable. The crops that have received the most research and development include hybrid poplars (fast-growing trees) and switchgrass (a perennial grass). Some information is also available on other tree crops, thick-stemmed perennials and annuals. Supplying large volumes of biomass to energy facilities on a daily basis requires that consideration be taken of the harvest timing, storage and delivery characteristics of different feedstocks as well as their yield, cost and energy properties. Our summary suggests that a combination of crops will be needed to provide large amounts of low-cost and environmentally sustainable year-round supplies of biomass feedstocks.