Abstract: In order to determine its genomic constitution, Hystrix duthiei ssp. longearistata was crossed with Psathyrostachys huashanica. Hybrids were obtained successfully from this combination. Morphology, fertility and chromosome pairing behavior in meiosis of the parents and their hybrids F₁ were investigated. The results showed obvious morphological differences between H. duthiei ssp. longearistata and P. huashanica, and intermediate spikes of the F₁ plants between the two parental species. The hybrids were completely sterile. Chromosome pairing at MI of PMCs in F₁ hybrids was relatively high and 55.12% of PMCs showed 5 or 6 bivalents per cell. Meiotic configurations were 9.83 Ⅰ + 5.46 Ⅱ+ 0.07 Ⅲ, with C-value of 0. 57, which indicated that H. duthiei ssp. longearistata and P. huashanica should share one Ns genome. The relationship between Hystrixand Leymus was also discussed.

Key words: Hystrix duthiei ssp. Longearistata, Psathyrostachy huashanica, Intergeneric hybrid, Meiosis, Genome, Chromosome pairing, Relatipnship