Morphologically intermediate plants between Arisaema sikokianum Franch. & Sav. and A. tosaense Makino were newly found in Tokushima Prefecture, Shikoku, Japan. Molecular analysis using PCR-RFLP of internal transcribed spacer (ITS) in nuclear DNA (nrDNA) indicated that these putative hybrids have a combined pattern of the two putative parental species. Moreover, the sequence results of chloroplast DNA (cpDNA) analysis of the putative hybrids were on the whole identical with both A. sikokianum or A. tosaense. The results suggest that the plants are hybrids between A. sikokianum and A. tosaense and that they have exchanged genes with the two parental species.

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Sex expression and pollination were examined in natural populations of Morinda umbellata subsp. umbellata (Rubiaceae), a woody climber distributed widely in southeastern Asia, including southwestern Japan. Sex expression of subsp. umbellata was confirmed as being functionally dioecious, with separate staminate and pistillate plants. Staminate flowers had four or five stamens and completely lacked a style and stigma, while pistillate flowers had a style with two stigmatic lobes and four or five abortive stamens, the anthers of which produced no functional pollen grains. The stigmas of pistillate flowers protrude beyond the corolla tube and are positioned above the anthers, whereas anthers of the staminate flowers protrude beyond the corolla tube, indicating that stigma and anther heights appear to be reciprocal between pistillate and staminate flowers. Both flowers produced nectar from the base of the corolla tube, and the nectar volume per flower did not differ significantly between the two sexual morphs. Various unspecialized, opportunistic insects, such as wasps, small bees, hover-flies, bee-flies, beetles, and butterflies, visited the flowers mainly to feed on nectar. Of these, small bees, wasps, hover-flies, and beetles appear to be effective pollinators of subsp. umbellata. The floral and reproductive characteristics of subsp. umbellata were compared with those of subsp. boninensis, which exhibits androdioecy.

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Herbarium specimens referable to Ceratopteris thalictroides in the sense of Lloyd were examined and the following cryptic taxa were recognized; C. thalictroides, C. gaudichaudii var. gaudichaudii, C. gaudichaudii var. vulgaris (var. nov.), C. oblongiloba (sp. nov.), and C. froesii. Compared with C. thalictroides s.str., C. gaudichaudii var. vulgaris is basically characterized by short stipes and dense pinnae, while C. oblongiloba is characterized by dense pinnules and narrowly oblong terminal lobes. A key to distinguish them and descriptions of the taxa are presented.

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As a result of a botanical expedition made as part of the Heart of Borneo Project, a new rheophytic aroid species, Piptospatha repens (Araceae: Schismatoglottideae) was found on the Sungai (River) Mendalam, a branch of the Sungai Kapuas, Putussibau, West Kalimantan, Indonesia.

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Plant diversity is poorly known on most tropical Asian islands, where many native species are under threat due to the rapid increase in non-indigenous plants. We conducted fieldwork to survey plant diversity on Lombok Island, Indonesia, an island where floral diversity has been poorly documented. Among the more than 800 angiosperm collections, 492 leaf fragments preserved for molecular analyses were identified using rbcL sequences as barcodes. Using Basic Local Alignment Search Tool (BLAST) searches against the entire DNA Data Bank of Japan (DDBJ) data sets yielded 314 haplotypes and 289 species in 265 genera and 87 families, determined by 96-100% sequence identity. While only 27 (8.6%) of the collections showed 100% sequence identity, the remainder (91.4%) exhibited less than 99% sequence identity. Those collections likely represent described or undescribed species, whose rbcL sequences have not yet been investigated. Since at least one species in every collection had a high similarity in the rbcL sequence, this method of species identification is of great use as a fast approach for surveying and analyzing largely unexplored tropical island floras.

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The distribution of Dryopteris caudipinna, a sexually reproducing counterpart of the apogamous species D. erythrosora, was investigated by counting the number of spores per sporangium in a large number of herbarium specimens. We discovered a number of new localities for D. caudipinna, including most of the major islands in the Izu Island arc (Tokyo Prefecture), and in Chiba, Aichi, Tottori, Yamaguchi, Kochi, Nagasaki, and Fukuoka prefectures. The habitat of D. caudipinna tends to be islands and coastal areas in warm temperate regions under the influence of warm currents.

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