Prometaphase and anaphase chromosome movements in living pollen mother cells

Chromosome movements during meiosis in three plant species are described. Pollen mother cells of Iris spuria L. (2n = 24), Allium triquetrum L. (2n = 18) and Tradescandia flumenensis Vell. (2n = 60) were studied. Mean prometaphase and anaphase chromosome velocities were approximately 0.5 mu m multiplied by min super(-1). Culture conditions had little effect on these velocities, but they may have delayed the onset of prometaphase or anaphase. Spindle elongation was zero during anaphase I in Allium triquetrum and in anaphase II in Iris spuria , but in both species elongation occurred during the other division of meiosis. Variations in anaphase I chromosome velocity at different positions across the Allium half-spindle were also observed.