Chromosome Numbers of Released Cultivars of Switchgrass, Indiangrass, Big Bluestem, and Sand Bluestem1

Chromosome numbers of cultivars of switchgrass (Panicum virgatum L.), indiangrass (Sorghastrum nutans L.) and the tall bluestem complex of big bluestem (Andropogon gerardi Vitman.) and sand bluestem (Andropogon hallii Hack.) were determined. Ploidy levels of these cultivars have not been reported previously even though these grasses have been reported to have two or more ploidy levels. Switchgrass cultivars ‘Pathfinder’, ‘Blackwell’, and ‘Nebraska 28’ were hexaploids (2n = 54), while ‘Summer’ and ‘Kanlow’ were tetraploids (2n = 36). Indiangrass cultivars ‘Nebraska 54’, ‘Oto’, ‘Osage’, and ‘Holt’ were all tetraploids (2n = 40). Big bluestem cultivars ‘Pawnee’ and ‘Kaw’ and the sand bluestem cultivar ‘Goldstrike’ were hexaploids (2n = 60). Meiosis was normal with bivalent pairing for most plants examined from all three grasses.