The ancestry of Hordeum depressum (Poaceae, Triticeae)

Based on morphological, cytological, and molecular data, three diploid Hordeum species have by various authors been suggested to may have participated in the ancestry of the tetraploid H. depressum . In order to test the different hypotheses we undertook hybridizations between the proposed taxa, H. brachyantherum ssp. californicum, H. intercedens , and H. pusillum . Autoploids and amphiploids were achieved by treatment of young shoots with colchicine. These were then hybridized with H. depressum and the resulting hybrid plants were tested for fertility. The results strongly indicate that H. depressum arose as a consequence of hybridization between H. brachyantherum ssp. californicum and H. intercedens , probably with H. brachyantherum ssp. californicum as the female parent.