The use of interspecific hybridization has been used by plant breeders to transfer desirable genes into crop plants. This study was undertaken to determine if Sorghastrum nutans (L) Nash (yellow indiangrass) and S. pellitum (Hack.) Parodi will hybridize, to investigate their cytotaxonomic relationship, and the possibility of using this species in the improvement of yellow indiangrass. Sorghastrum nutans has 40 chromosomes that pair as 20 bivalents during meiosis with no abnormalities, suggesting it is an allotetraploid. Sorghastrum pellitum is a diploid with 20 chromosomes that pair as 10 bivalents during meiosis with no abnormalities. Three triploid interspecific hybrids between hybrids between S. nutans and S. pellitum were produced. Based upon spikelet characteristics, they are morphologically closer to the S. nutans than S. pellitum, female sterile, and the stainable pollen ranged from 0.0 and 2.8%. Chromosome associations during meiosis indicate that S. nutans and S. pellitum have one genome in common and that two homozygous translocations between chromosomes of two genomes in S. nutans may exist.