A new monotypic genus, Pseudotrismegistia H. Akiy. & Tsubota, is proposed to accommodate P. undulata (Broth. & Yasuda) H. Akiy. & Tsubota. Pseudotrismegistia differs from the widely distributed genus Trismegistia in the weak differentiation of leaf shape between stems and branches, strong undulation in the upper portion of the leaf lamina, clearly differentiated forked costae of leaves, absence of well-marked borders at the leaf margins, and the alar cells arranged in a scalariform manner. The nearly equal size of alar cells that are scarcely inflated, as well as molecular analyses, suggests the genus should be assigned to the Heterophylliideae of the Sematophyllaceae.

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A new species of Podostemaceae, Cladopus javanicus, is described from West Java. It is a second Malesian species of Cladopus and differs from the other congeneric species including Cladopus nymanii and Torrenticola queenslandica in the long shoots and densely imbricate digitate leaves.

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The taxonomy of the Lauraceae in Southeast Asia is still in confusion because of the lack of recent comprehensive revisions. In an effort to reduce this confusion, a checklist of Beilschmiedia in Borneo is presented. As a result, 29 accepted names of Beilschmiedia are recognized in Borneo, including one new species. Seventeen unpublished names are recorded on several specimens and have caused part of the confusion. Among the seventeen names, seven are identified with names already published and three are combined and used to describe a new species, Beilschmiedia hartonoana. Seven unpublished names could not be resolved because of an insufficient number of specimens.

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Stigma height, anther height and stigma-anther separation were studied to examine their dimorphic nature in two populations of Prunus nipponica occurring in sub-alpine zone of Mts. Norikura and Utsukushigahara, central Honshu of Japan. The stigma and anther heights considerably varied among the plants and each of the characters showed normal frequency distributions within populations. However, stigma-anther separation showed a bimodal distribution. Based on this floral character the populations concerned were tentatively divided into two discrete floral morphs : long (L)-styled morph and homo (H)-styled morph. Each of the two morphs was highly constant within a plant and did not change its floral nature for over two years. Artificial pollination experiments indicated that the two morphs were strongly self-incompatible and crosses between the same morphs (HxH or LxL) produced seeds in higher percentage. These results suggest that the dimorphic nature in P. nipponica does not exhibit an ordinary heterostyly but may be regarded as an example of herkogamous polymorphism. We briefly discuss on the possible adaptive significance of dimorphic natures of the flowers exhibited by P. nipponica.

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Chromosome numbers are reported for 10 species of ferns from Guam. The report includes the first cytological records for Lygodium auriculatum (2n=c. 56, 2x) and Pteris spinescens (2n=58, 2x). The cytotypes of the pteridophytes examined generally showed the same ploidy level as those of neighboring regions. Phymatodes scolopendria is a tetraploid with 2n=144, the same as south Indian and Taiwanese populations, although diploids with n=36 are widely distributed from Africa to southern China. The cytogeography of the six species complex is noted.

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Peucedanum japonicum comprises three allopatric varieties : var. japonicum, var. latifolium, and var. australe. Allozyme analysis was employed to estimate levels of genetic variation within and among populations of these varieties and to show whether the genetic differentiation is correlated with the three varieties. A UPGMA dendrogram defines three main clusters. These clusters are not concordant with the three varieties. Mean levels of expected heterozygosity showed that the Japanese mainland and the northern Ryukyus populations have low genetic variation and the central Ryukyus populations have high genetic variation. Genetic differentiation of P. japonicum may strongly reflect the geological history of the Ryukyu Islands.

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Cytological investigations were carried out on 24 taxa representing Aristolochia subgenera Siphisia and Aristolochia. Of them, 17 taxa (16 species and one variety) were examined for the first time. In subgeneus Siphisia, all the eight species, A. austoyunnanensis, A. kwangsiensis, A. macrophylla, A. moupiensis, A. nakaoi, A. paracleta, A. salvadorensis and A. tricaudata show the same number of 2n=32. While in subgenus Aristolochia three different chromosome numbers were observed ; 2n=16 in A. maxima and A. ovalifolia ; 2n=14 in A. arcuata, A. argentiana, A. clematitis, A. cymbifera var. abbreviata, A. fimbriata, A. goliathiana, A. macroura, A. micrantha, A. odoratissima, A. ringens and A. tiangularis ; 2n=12 in A. jackii, A. kankauensis and A. tagala. The chromosome numbers obtained are relatively well in congruence with the classification system and with the molecular phylogeny. Based on the present and previous studies the subgenus Siphisia is characterized by the number 2n=32. In contrast, the subgenus Aristolochia is diversified in chromosome number, showing the three different numbers. Subsection Podanthemum and series Thyrsicae seem to be characterized by the numbers, 2n=12 and 2n=16, respectively.

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A putative hybrid of the fern genus Pteris was collected on Okinawa Island. It was morphologically intermediate between P. ryukyuensis (section Pteris) and P. semipinnata (section Campteria), suggesting that it might be an intersectional hybrid between them. The hybrid nature of the plant also suspected because of the abnormal morphology of the spores and sporangia. To clarify the parcentage of this putative hybrid, we analyzed the nuclear (nDNA) and chloroplast (cpDNA) DNA of all three of them. PCR analysis of the internal transcribed spacer 1 region of the nDNA indicated that the putative hybrid possessed nDNA of P. ryukyuensis. Furthermore, PCR-SSCP analysis of the intergenic spacer between psbC and trnS of cpDNA showed the putative hybrid to have the same electrophoretic pattern as P. semipinnata. Because the cpDNA is generally maternally inherited, we concluded that the putative hybrid was an intersectional hybrid between P. ryukyuensis and P. semipinnata, with the latter species functioning as the mother.

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