The partitioning and quality of aboveground biomass have important ramifications for crop management and biomass conversion. In preliminary studies, Saccharum sp. x Miscanthus sp. hybrids exhibited stubble cold tolerance in west-central Arkansas, unlike Saccharum sp. x Saccharum spontaneum hybrids. The objective was to examine foliar and stern quality of the C-4 grasses Miscanthus sinensis ('Gracillimus'), Miscanthus x giganteus (Q42641, proprietary), Panicum virgatum ('Alamo'), and two F, hybrids of Saccharum sp. x Miscanthus sp. (US84-1028 and US84-1058) in a field study during 2004 (plant cane) and 2005 (first stubble) near Booneville, AR. Switchgrass produced more stems m(-2) than the other entries both years, and there was little difference in stein number among other entries. Clone US84-1028 yielded more dry mass m(-2) than other entries in plant cane, while switchgrass, US84-1028, and M. x giganteus did not differ in first stubble. Clone US84-1028 also had more stern dry mass and leaf dry mass than other entries both yr. Tissue N concentrations were low for these entries, but leaves contained about twice the N of stems (<= 15.2 and 7.8 g kg(-1) respectively). Leaves represented as much as one-third of total biomass, and had large cellulose (<= 482 g kg(-1)) and lignin (167 g kg(-1)) concentrations. The competitively high biomass yield of this small sample of sugarcane alleles should encourage the expansion of the crop beyond its current production regions. Sugarcane and M. x giganteus should be examined in higher-input temperate systems because of their bioenergy potential. Published by Elsevier Ltd.