Cytogenetic Studies of Some Members of Polygonaceae of Kashmir

III. Rheum L

Abstract

Meiotic details of two species of Rheum have been studied. R. emodi, a dip-ploid species with 2n=22 chromosomes, an accessory chromosome was observed in most of the pollen mother cells studied. In 27% pollen mother cells this B chro-mosome was observed attached to one of the bivalents by a faintly staining connection. It is the first report of the presence of an accessory chromosome in this genus.
Meiosis in both R. webbianum, a tetraploid species with 2n=44, and diploid R. emodi was mostly normal. The frequency of mutivalents in R. webbianum was very low, which may probably be due to its amphidiploid nature.