The use of flow cytometry for evaluation of plant chromosomes requires some specialized attention to preparation and instrumentation. This unit deals exclusively with plant cytogenetics and presents an outline of this area as well as methods for accumulation of cells in metaphase, preparation of chromosome suspensions, flow analysis and sorting of chromosomes, and processing of the sorted chromosomes. Each method is described in tremendous detail because in many aspects dealing with plant cells is quite different from dealing with mammalian cells. Supporting histograms are presented as well as a range of special hints on dealing with plant material and a discussion of the utility of sorted chromosomes for plant genome mapping.