The relationship between some Eurasian and American species ofBromussection Pnigma as determined by the karyotypes of some F1hybrids

摘要

Interspecific hybrids were successfully produced, using embryo culture, between Eurasian and American species ofBromussection Pnigma. Cytological observations on satellite type and chromosome size suggest that the two Eurasian speciesB. benekenii(Lange) Trimen andB. ramosusHuds. are more closely related to the American species (B. ciliatusL.,B. latiglumisHitchc.,B. pacificusShear, andB. richardsoniiLink) 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.