CYTOGENETICS AND MORPHOLOGY OF ELYMUS-PANORMITANUS VAR HETEROPHYLLUS AND ITS RELATIONSHIP TO ELYMUS-PANORMITANUS VAR PANORMITANUS (POACEAE,TRITICEAE)

Elymus panormitanus var. heterophyllus, PI-235086, was collected in Is rael and became part of the National Plant Germplasm System as Elymus caninus L. in 1956. Bivalent pairing at metaphase I (MI) in E. panormi tanus var. heterophyllus (2n = 42) was typical of other allohexaploids within the Triticeae. However, chromosome pairing analysis at MI of t he tetraploid hybrids with Pseudoroegneria spicata (2n = 14, SS) and t he pentaploid hybrids with Pseudoroegneria stipifolia (2n = 28, SSSS), Elymus lanceolatus (2n = 28, SSHH), E, panormitanus (2n = 28, SSYY), and Elymus nevski (2n = 28, SSYY) indicated that two of the three geno mes of E, panormitanus var. heterophyllus were at least partially homo logous to the S genome and confirmed the presence of a Y genome. Clust er analysis of 18 key characters separated E. panormitanus var. hetero phyllus from E. panormitanus. However, the continuous variation betwee n the two taxa made taxonomic separation difficult unless the samples represented the two extremes. In this unique case, two taxa-E. panormi tanus var. heterophyllus and E. panormitanus-were very close morpholog ically but different genomically. Elymus panormitanus var. heterophyll us is a hexaploid (SSSSYY 2n = 42) and E. panormitanus is an allotetra ploid (SSYY; 2n = 28).