The taxonomy of members in the Arisaema undulatifolium group is revised based on the comparison of eleven morphological traits of 1303 plants from 33 populations. Based on the mean values of six morphological traits for each population, six groups were recognized by cluster analysis. Significant differences among these six groups were found in number of leaflets, width of leaflet, width/length ratio of leaflet, length ratio of peduncle/petiole, auricle size, purple pigmentation and number of ovules per ovary. Five groups recognized by cluster analysis correspond to the existing species, A. aequinoctiale, A. limbatum, A. minus, A. nambae and A. undulatifolium. The sixth group is newly described as A. undulatifolium Nakai subsp. uwajimense T. Kobayashi et J. Murata, which is distinguished from subsp. undulatifolium by the higher width/length ratio of leaflet, the longer peduncle and the more numerous ovules per ovary. Arisaema limbatum var. stenophyllum and A. undulatifolium var. yosinagae and A. limbatum var. aequinoctiale in the sense of Serizawa in J. Jap. Bot. 55, 148-156 (1980) could not be distinguished from each other by any morphological traits examined, and they are thus regarded as a single entity, A. aequinoctiale. Arisaema limbatum var. conspicuum and A. limbatum var. limbatum could not be distinguished from each other.

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A new variety, Carex foliosissima F. Schmidt var. pallidivaginata J. Oda & Nagam., is newly described. It is distinguished from the type variety by the pale green basal sheaths, turning light brown on drying, and perigynia with invisible or inconspicuous veins. It is also distinct in the leaf anatomy; the leaves of the new variety are thinner and the second layer of bulliform cells (hinge cells) is thinner than that of var. foliosissima. Variety pallidivaginata is distributed from the upper beech forest zone to the subalpine zone on the Japan Sea side of central and northern Honshu, and in southernmost Hokkaido, at higher elevations than var. foliosissima which usually occurs from the lowland to lower montane zones. Variation in the leaf width of C. foliosissima was examined and the results did not support the wide leaved form ('var. latissima' Akiyama) as a distinct variety.

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Cynanchum yonakuniense, a perennial twining herb, endemic to Yonaguni Island, the Ryukyu Archipelago has never been recorded since its original materials collected there. We rediscovered it on the island and moreover found a herbarium specimen of the species on Senkaku Islands in the same archipelago. In this paper we added the morphologies of root, fruit and seed to the description of this species. On the basis of morphological re-examinations, we propose a new combination Vincetoxicum yonakuniense.

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In order to examine possible nucleotide sequence variations in the rbcL gene of Conocephalum japonicum, we collected plant materials from 52 localities representing the geographical distribution of the species in Japan. We determined 1304 nucleotide sequences and found two kinds of rbcL sequences differing by 6 nucleotides. Their distribution areas were clearly demarcated as north or south of latitude 42-43°N in Hokkaido. We identified the two rbcL types as JN (Japan North) and JS (Japan South) types. The geographical boundary of these two rbcL types is nearly identical to the northern limit of the distribution range of Fagus crenata in Japan. We could not find any morphological differences between the JN and JS types. In Abuta, Hokkaido, the two rbcL types were growing together within small research areas measuring 25m×15m (JN type: 10 and JS type: 8 individuals). We performed an allozyme analysis on this population, and observed tight associations between the allozyme and rbcL variations: the JS type had Est-3a and Tpi-1a alleles, whereas the JN type had Est-3b and Tpi-1b. These findings suggest that these two rbcL types of C. japonicum might be two reproductively isolated cryptic species.

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Genetic diversity and species relationships among ten species of Utricularia were investigated using inter simple sequence repeat (ISSR) markers. Six primers generated 236 ISSR fragments across the ten species with an average of 39.3 fragments per primer. Utricularia longifolia presented the highest number of fragments whereas U. amethystina, U. humboldtii and U. uliginosa provided the least. The highest similarity was detected between U. alpina and U. longifolia among the species studied while the highest pairwise genetic distance was found between U. caerulea and U. longifolia. Principal coordinate analysis was conducted to view the clustering pattern of the taxa which revealed that U. alpina and U. longifolia clustered together whereas U. amethystina, U. bifida, U. caerulea, U. calycifida, U. humboldtii, U. praelonga, U. triflora and U. uliginosa formed another cluster.

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To determine genetic variation in the apogamous fern species Dryopteris nipponensis, allozyme analysis was carried out. Among the 196 individuals of D. nipponensis examined, 45 electrophoretically distinguishable variants were detected. This is the largest number of electrophoretic variants found in one apogamous fern species so far examined. Only one variant was characterized by a unique allele. All of the other variants were distinguished by the combinations of the limited number of alleles that were shared by some variants. The evidence strongly suggests that this apogamous species is of recurrent origin. The possibility of homoeologous chromosome pairing was also evaluated. Theoretically, genotypes of twelve of 45 variants can be generated from those of other variants via homoeologous chromosome pairing.

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Cayratia japonica showed intra-specific polyploidy of x=20, i.e., 2n=40 (diploid) and 60 (triploid). Individuals with 2n=40 produced fruits, and formed 20 bivalents at metaphase I in meiosis, but their pollen fertilities widely varied from about 30 to 90%. Individuals with 2n=60 did not produce any fruits, formed a variable number of trivalents, bivalents and univalents at metaphase I, and showed low pollen fertilities of less than 30%. The possible occurrence of some genetic types for pollen development in diploids is discussed.

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Nymphoides indica (L.) O. Kuntze (Menyanthaceae) is a perennial, floating-leaved, heterostylous, aquatic plant. In this paper the dimorphism of the flowers including differences in the distance between staminate and carpellate parts and differences in pollen size between long-styled and short-styled floral morphs is documented. Seed set was observed only in intermorph pollinations. Nymphoides indica was confirmed to be heterostylous, herkogamous and self-incompatible.

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A range extension for Tamijia flagellaris is reported from the upper Tatau River in Bintulu District, Sarawak, Malaysia. A brief description of the fruit, which was unknown prior to this report, is also given.

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