Acceptance and deployment of leading candidate cellulosic energy crops has been significantly inhibited by their lack of providing both inexpensive seeded establishment options and high first-year biomass production in perennial feedstocks with mitigated risk of crop invasiveness. Pearl Millet-Napier grass (‘PMN’; Pennisetum glaucum R. Br. x P. purpureum Schumach) and King grass (‘KG’; P. purpureum x P. glaucum), in comparison, are perennial biomass crops with immense potential to combine both the high yields of tropical perennial grasses such as energy cane (Saccharum spp.) and the integrated agronomics of large-seeded annual grasses such as sorghum (S. bicolor [L.] Moench). PMN and KG are further unique among energy grasses as ‘seeded-yetsterile’ (SYS) feedstocks, in which fertile parents allow seeded production of hybrids that are subsequently sterile in biomass production fields.