Cytomixis and Unreduced Pollen Grain Formation in Alopecurus L. and Catbrosa Beauv. (Poaceae)

Meiotic studies were performed on the populations of four Alepecurus L. species and varieties as well as five populations of two Catabrosa species. Alopecurus textilis showed 2n=8x=56 chromosome number, the varieties of A. myosuroides var. myosuroides and A. myosuroides var. breviaristatus showed 2n=2x=14 and A. arundinaceus possessed 2n=6x=42. Catabrosa aquatica and C capusii showed 2n=4x=20 chromosome number. The chromosome numbers of A. textilis, A. myosuroides var. myosuroides and A. myosuroides var. breviaristatus and C capusii are new to science, while hexaploid level is new for A. arundinaceus. Tetraploid and octaploid species of Alopecurus and Catabrosa studied formed bivalents in metaphase of meiosis-I, which is considered a diplontic behavior for polyploid species. Grouping of the species by clustering methods based on relative cytogenetical characteristics showed good separation between Alopecurus and Catabrosa species indicating the cytogenetic distinctness of these two grass genera. Cytomixis and chromosome migration occurred in most of the species and populations studied forming aneuploid and polyploid meiocytes. Unreduced pollen grains were formed possibly as a result of cytomixis in the species studied.