The Phragmites communis Trin. chromosome complement in the Danube Delta

Summary This study elucidates the caryotypes in two varieties of Phragmites communis of the Danube Delta, by means of an original squash technique.The two varieties studied above coexist in the floating reed biocoenosis, but there exist different masses without any transitory forms. The flavescens and gigantissima varieties have different morphophysiological characteristics, the latter variety flowers later and shows the gigantism characteristics of polyploids.Comparative analysis of the caryotypes of the two varieties shows that the variety gigantissima is probably a natural auto-octopolyploid (2n = 8x = 96) of a relatively recent origin, as the chromosomes can be grouped into units of 4. The origin of the flavescens variety (2n = 4x = 48) is not certain, because the chromosomes can only be grouped in pairs within the caryotype. It seems that this variety, widespread all over the earth, has an older origin, since the rearrangements determining the present configuration of the caryotype occurred at chromosome level.