The relationship between some Eurasian and American species of Bromus section Pnigma as determined by the karyotypes of some F1 hybrids

Abstract

Interspecific hybrids were successfully produced, using embryo culture, between Eurasian and American species of Bromus section Pnigma. Cytological observations on satellite type and chromosome size suggest that the two Eurasian species B. benekenii (Lange) Trimen and B. ramosus Huds. are more closely related to the American species (B. ciliatus L., B. latiglumis Hitchc., B. pacificus Shear, and B. richardsonii Link) than to other Eurasian species. It is suggested that the section Pnigma may contain two distinct groups of species that can be separated on the basis of chromosome size.