Meiotic Aberrations and Sterility in Alopecurus Myosuroides Huds

EVERAL investigators have dealt in more or less detail with the S cytological behaviour of various species belonging to the gramineal genus Alopecurus.Somatic chromosome numbers, for instance, have been determined by MARCHAL ( 1920), KATTERMANN (1930), AVDULOV (1931), FLOVIK (1938), STRELKOVA (1938), and JOEINSSON (1941).Studies of meiosis have been published by CHURCH (1929), RANCKEN (1934), FLOVIK (1938), and JOEINSSON (1941).The relation between chromosome number and geographical distribution has been treated by STRELKOVA (1938), while JOEINSSON (1941) has described the cytogenetics of a number of artificial species hybrids.Through these investigations a not inconsiderable knowledge of the cytogenetical structure of the genus has been gained.The chromosome numbers within the genus are built up on the basic number 7. Diploid, tetraploid, octoploid, decaploid, and approximately 16-ploid species occur.The total area over which the genus is distributed extends over practically the whole of the frigid and temperate zones of the northern and southern hemispheres.The diploid and tetraploid species, OVEZIMNICOV'S (according to STRELKOVA, 1938) groups Annuae, Pratensae and Ventricosue, cover the greater part of the range and are especially bound to the damper meadow lands of the lowlands.The octoploid species constitute a taxonomically and geographically well defined group, the group Vayinatae (OVEZIMNICOV), which has its chief range in the mountainous regions of West Asia.The high-chromosomal species, finally, occur along the coasts of the Polar Seas, both the Arctic and Antarctic.The diploid and tetraploid species represent two types with regard to chiasma morphology.At I-M one type has completely terminal chiasmata, the other is entirely non-terniinalizing.In the tetraploid species quadrivalents occur in low frequency, and in the high-chromo-soma1 there is some multivalent frequency.Some species hybrids are spontaneous, and after artificial pollination the species hybridize more Hereditas XXS.