A Cytological Study of a Triploid Rhoeo discolor

Abstract

Triploid Rhoeo discolor exhibits various chromosomal configurations at diakinesis and metaphase-I. These are univalents, chains of from 2-18 chromosomes, rings containing from 2-4 chromosomes. Triple chiasmata is commonly observed in the triploid. Diploid Rhoeo discolor forms a circle of twelve chromosomes at meiosis. Interstitial chiasmata is reported in 2 cells in the triploid. Pollen fertility is much higher in the diploid than in the triploid. Laggards at anaphase-I and the degeneration of one or more cells in a tetrad is frequently observed in the triploid. The segmental complex formula can be explained on the basis of the complex of diploid Rhoeo, this having a circle of 12 chromosomes. A segmental formula has been evolved for the triploid in which it is supposed that the configuration at diakinesis would be a ring of ring bivalents and rod chromosomes joined together alternately.