| Morphologically the species under the genus Eremopyrum (E. triticeum,
E. hirsutum, E. Bounapartis, E. orientale, and E.
distans) seem to form a homogeneous group. To find a correlation at
the cytological level, the karyotype analyses of the available species of
this group have been undertaken. The results are summarized below. The karyotype of Eremopyrum triticeum (2n=14) has been found to be very different from all other groups of Triticeae that have so far been investigated. All of its chromosomes show subterminal centromeres with one of the arms reduced to a knoblike head (Fig. 1on the cover). This is in contradistinction to the median or submedian centromeres of the chromosomes of all other groups studied in the wheatgrasses. Eremopyrum hirsutum (2n=14) is remarkably similar in floral morphology to E. triticeum, and particularly to E. Bounapartis, the only distinguishing character from the latter species being the hairiness of its spikelets. The external morphological similarity finds corroboration in the morphology of the chromosomes. The karyotype of E. hirsutum differs from that of E. triticeum in that two pairs of its chromosomes have relatively longer distal arms instead of knob-like heads (Fig. 2 on the cover). From the point of view of chromosome morphology Eremopyrum orientale (2n=28) shows a mixture of two groups of chromosomes. Fourteen of its chromosomes are similar to those of E. triticeum, while the other fourteen have median or submedian centromeres. This might be indicative of its being an amphidiploid between two diploid species which contribute the two different groups of chromosomes. The present study is in conformity with the observations of AVDULOV (1931), who, although he recognized the diversity in the karyotypical pattern within Agropyron, did not think it necessary to separate triticeum and its relatives into a new group. The present writer, however, is of the opinion that the peculiar chromosome morphology together with the genetical data of sterility barrier between Eremopyrum triticeum and other members of Triticeae, definitely strengthens the validity of the new genus Eremopyrum. |
| <-- Back |