Two new species, Vincetoxicum izuense and V. hoyoense, are described here. Vincetoxicum izuense is a twining perennial herb on rocky beaches and on the margins of thickets near the sea and is endemic to the southern Izu Peninsula. It resembles V. sublanceolatum and V. japonicum, but V. izuense is distinguished from them by the leaves, follicles and trichomes on the lower surface of the leaves. Vincetoxicum hoyoense is a large, perennial, twining herb on rocks and on the margins of thickets facing the sea and is endemic to the area around the Bungo Channel. Vincetoxicum hoyoense resembles V. japonicum f. puncticulatum and V. sublanceolatum, but V. hoyoense can be distinguished from them by the larger, elliptic or ovate leaf blades with shallowly cordate base and the longer corolla lobes. Although V. hoyoense also resembles V. izuense in flower, morphology and leaf shape, V. hoyoense is easily distinguished from it by the large ovate or elliptic leaves with shallowly cordate base and the large corollas.

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In our previous study, we found two rbcL types (JN and JS types) in Japanese Conocephalum japonicum Grolle. In this study, we collected plant materials from 20 localities in China, Korea and Taiwan. We determined 1304 bps of each nucleotide rbcL sequence and found two rbcL types in Asian C. japonicum. One of them was a new rbcL type (CS type), which differs from the JN and JS types by 10 and 8 nucleotides, respectively. The CS and JS types were found both in Mainland China and Taiwan. We could not find any morphological differences between the two types. In Chitou, Taiwan, the two rbcL types were growing together within a small research area measuring 100m×200m. We performed an allozyme analysis on this population and observed that the CS type had Est-4a and Tpi-la alleles; whereas the JS type had Est-4b and Tpi-1b. It was strongly suggested that these two rbcL types might be reproductively isolated cryptic species of C.japonicum.

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Picea koyamae is a species which is distributed scarcely and is threatened to extinction, though the details are not well known. We investigated the geographical distribution and genetic variation of this species. Seven habitats over the Yatsugatake mountains and Akaishi mountains were confirmed in this study, and it was estimated that in these areas combined there were less than 1,000 living mature trees. Genetic diversity within and among 4 populations was analyzed using allozymes. The mean genetic variation within populations was in the range of general long-lived tree species. However, genetic variation in the Karamatsu-sawa population at Yatsugatake mountains showed a rather low value. It is conceivable that this population has experienced a bottleneck effect. The genetic differentiation among 4 populations was found to be at an intermediate level between continuously distributing conifers and discontinuously distributing ones. In this study, "P. shirasawae" was suggested to be merely a morphological variation within a population of P. koyamae, and was treated as P. koyamae in our results.

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Geographical patterns of the genetic differentiation of Angelica japonica and Farfugium japonicum were analyzed using allozyme analysis. Many rare alleles were found only in the southern Ryukyus populations of A. japonica and F. japonicum. Few rare or area-unique alleles were found in the northern Ryukyus or northward populations of these plant species. Genetic diversity (expected heterozygosity) of these plant species showed loss of genetic diversity in populations of a lower altitude island. The populations in low altitude islands might have been recolonized when the islands resurfaced after submersion. A geographical cline of the genetic diversity, which decreased from the central Ryukyus populations to the northward, was found in this study. These geographical patterns, which were common for these plant species, indicate that the southern Ryukyus populations were isolated from those of other areas for a long period, and the northern Ryukyus and populations northward might have recolonized rapidly from the central Ryukyus after the last glaciation.

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Rhododendron indicum f. otakumi is an endemic rheophyte on Yakushima, Japan. The morphology and anatomy of the leaves of R. indicum f. otakumi and R. indicum f. indicum, its putative ancestor, were examined to determine differences between them. The leaves of f. otakumi are narrower than those of f. indicum, with leaf length to width ratios of 5.10 and 3.38, respectively. Our examination revealed that stenophylly in R. indicum f. otakumi was due to a decrease in the number of cells across the width of the leaf in both the adaxial epidermis and palisade tissues, even though the leaf cells of the epidermis and palisade tissue were larger in R. indicum f. otakumi. The heavy rainfall on Yakushima may have been a factor in the evolution of the narrow leaved form of R. indicum.

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The sexual mode of Wikstroemia pseudoretusa, endemic to the Bonin (Ogasawara) Islands, was examined and compared with that of W. retusa, distributed widely in the Ryukyu Islands, Taiwan and the Philippine Islands. Although the two species have generally been regarded as hermaphroditic, we found that W. pseudoretusa was actually dioecious and W. retusa was hermaphroditic. In plants of W. pseudoretusa, male flowers usually produced functional pollen grains, and their gynoecium was vestigial and lacked ovules, while female flowers had a functional gynoecium, including an ovule, and their anthers were vestigial and completely lacked pollen grains. Based on the morphological properties of these species and on the occurrence of hermaphroditism in a closely related W. retusa, distributed on the continental islands, the Bonin W. pseudoretusa seems to be an example of dioecy evolving from hermaphroditism within the Islands.

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Dendranthema coreana, which occurs at high altitudes on Mt. Halla, Jeju-do, Korea, is a small perennial herb with large, solitary heads. The species was found to have a chromosome number of 2n=90, which is decaploid (based on x=9) and the highest level of polyploidy in Dendranthema in Korea.

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