A karyotypical study of the Trillium plants has revealed an interesting fact that all the members of the genus possess the morphologically closely similar basic complement consisting of 5 chromosomes A, B, C, D and E. From this and certain other view points, in his previous paper, the writer suggested that the tetraploid species should be allotetraploids or that they may have originated through hybridisation in the course of evolution (HAGA 1934). a b C Fortunately in the. year 1935 the writer

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... ound a natural hybrid (2n=I5) which arose very probably from the spontaneous hybridisation between Trillium kamtschaticum (2n=IO) and Trillium Tschonoskii (2n=30)1) ; this 1) This combination of the hybridisation was ooncluded with high certainty from the external morphology, ecological aspects, crossability, and from the number, morphology and behavior of the chromosomes (v, infra; Cf. HAGA 1937b). 2) In reality this plant is only a hybrid having no second generation equivalent with the parent, keeping its Fl characters merely by its perenial habit. So the present taxonomic name was used only for convenience of description.