As to the trend of karyotype evolution in Lycoris, Inariyama (1951aInariyama ( , 1951b) ) proposed a fusion hypothesis.He considered that the various karyotypes of fertile diploid species of this genus must have had their origin in the karyotype of L. sanguinea composed of twenty-two I-shaped (acrocentric sensu lato) chromosomes alone, and the most advanced karyotype of L. aurea composed of ten V-shaped (meta or submetacentric) chromosomes and two I-shaped chromosomes were derived from the former by successive fusions of any two I-shaped chromo somes.While he considered that the karyotypes of sterile species such as L. albiflora, L. squamigera and L. radiata were produced by hybridization and/or polyploidization.Nmaely, in his opinion, the basic chromosome number of Lycoris is not x=6, the lowest haploid num ber in the genus, but x=11.Recently, Jones (1978) and Nishikawa et al. ( 1979) supported Inariyama's hypothesis.On the other hand, however, Darlington (1963) and Flory (1977) considered that I-shaped chromosomes must have been originated from the fission through the centromeric region of V-shaped chromosomes in this genus.Instead of I-shaped and V-shaped chromosomes, the present author recognized three major types of chromosome, M, T and A (1986).Moreover he observed various types of intraspecific structural and numerical chromosomal changes of the karyotype involving some mutant chromosomes such as M', T', m and a (Kurita 1987a(Kurita , 1987b(Kurita , 1987c(Kurita , 1988c)).In this paper, he summarizes and itemizes the modes of karyotype alterations, and then the problem of the trend of karyotype evolution in this genus is discussed based on his observations and the data obtained by many previous cytologists.The chromosome numbers of Lycoris species so far known are summarized in Table 1.
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Siro Kurita (1988) studied this question.