Attributes ofCalamagrostis langsdorffii,C. sachalinensis and their intermediates in Shikoku

The internal structure of theCalamagrostis langsdorffii-sachalinensis complex in Shikoku was examined on the basis of a number of new collections. Chromosome counts disclosed the occurrence of the following entities: 6X and 8X, as well as some aneuploids, ofC. longsdorffii; 6X ofC. sachalinensis; 6X and 8X of the intermediates between these two species. The examination of pollen of these collections and the herbarium specimens showed that all of them may be apomictic in seed formation and that the sexual tetraploids of the pertinent complex may not be distributed in Shikoku. Details of morphological features of the collections were analyzed, and the intermediacy in morphology of the group “intermediate” was confirmed by the distance diagram method. The collections ofC. langsdorffii from Shikoku generally showed an awn longer than that of the collections from Honshu and Hokkaido. On the basis of these and some other observations, relationships of the strains extant in Shikoku were discussed. For the derivation of the present-day composition of the pertinent complex, an hypothesis which is founded on the presumption of a past occurrence of sexual tetraploids of bothC. langsdorffii andC. sachalinensis in Shikoku has been advanced.