CHROMOSOME MORPHOLOGY IN THE GENUS AVENA

The chromosomes of the Avena species were studied and their karyotypes established. The karyotype of the diploid species (excluding A. longiglumis) is designated as A. Longiglumis has a different karyotype with at least three chromosomes that have major changes. This karyotype is a modified A, designated as A′. The designation of the tetraploid karyotype is AB, including the basic set of chromosomes A and a second completely different set B. In the hexaploid species the basic set A is present but the B set is not; therefore the proposed designation is ACD. These results indicate an alloploid origin for the polyploid species.