Effects of photoperiodic conditions leading to the formation of flowers on sections excised from the internodes of flower stalks were studied. (The results obtained are summarized in Table 1.) Flower formation was induced by long days, whereas short days had little effect. When culrtures were placed in darkness for more than two weeks, the tissues almost lost their ability to form flowers. The tissues were most responsive to photoperiodic treatments during the second week of culture. Long day conditions induced flower bud formation in 100% of the sections during the third and fourth weeks. When the explants were kept for periods of up to ten weeks or more, about 70% of those under short day conditions produced flowers. However, the number of flower buds remained small in comparison with similar cultures held under long day conditions (Table 2). The significance of the results obtained for the understanding of the roles of long days, short days and continuous darkness on the process of flower formation is discussed.
1. The distribution area formerly known for Kalimeris incisa DC. in Japan was from Kyushu to Kinki District of Honshu. The present investigation revealed that the distribution of this species extends eastward into the western and southern lowlands of Chubu District in central Honshu. 2. At many localities within the distribution area, K. incisa was growing together with a morphologically similar heptaploid sepcies K. yomena. But K. incisa seemed to prefer habitats a little drier than those of K. yomena. 3. Except some insular and periferal populations, K. incisa showed a high degree of individual variability, and the range of variation at any one locality closely approximated that which occurs over the entire species range in Japan. 4. The results of a chromosome count revealed that K. incisa in Japan is nearly stable as an octoploid species with 2n=72. It showed, however, a peculiar pattern of variation in chromosome number that the frequency of aneuploids with 2n=71 or lower chromosome numbers is much higher than that of aneuploids with 2n=73 or higher chromosome numbers. 5. Some clones were found to include one or two large chromosomes in their somatic chromosome complements. Those chromosomes are presumably derived from a species of Aster.
1) In this paper the author deald withh the chromosome numbers and the karyotypes of the following four species of Hosta: H. montana, H. lancifolia, H. chibai and H. capitata. 2) The chromosome numbers of the four species were 2n=60. 3) The karyotypes of the three species (H. montana, H. lanci folia, H. chibai) were as follows: they were classified into 30 pairs, which were divided into four pairs of large chromosomes, two pairs of medium, and 24 pairs of small ones. One of the two pairs had satellites. 4) In H. lancifolia karyotypes of the clones from different source differed more or less in the number of large chromosomes and in the number of satellite chromosomes. 5) The karyotype of H. capitata differed from those of the other three species in two satellite chromosomes of large chromosomes and in the position of primary constriction in three pairs of large chromosomes.