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Arisaema tosaense Makino develops either 1 or 2 leaves during both the male and female phases. To clarify the relationship between growth stage (sexual stage) and leaf number in this species, we conducted morphological analysis using A. tosaense, A. japonicum Bulme, A. sikokianum French. & Sav., and A. ringens (Thunb.) Schott. We found that increase in size of pseudostem of these Arisaema species is correlated to changes in the growth stage from sterile to male and from male to female phases. In particular, 1-leaf individuals of A. tosaense appeared at the beginning of both male and female phases, suggesting that they contribute to the earlier appearance of the fertile phase from sterile stages

Morphologically putative introgressive hybrids of Arisaema sikokianum Franch. et Sav. and A. tosaense Makino were newly found in Kochi and Tokushima Prefectures in Japan. All the individuals have the same morphological characteristics as A. tosaense excluding a purple spathe. Molecular analysis using PCR-RFLP of internal transcribed spacer (ITS) in nuclear DNA (nrDNA) indicates that these putative introgressive hybrids have the same pattern as A. tosaense. Moreover, the sequences of chloroplast DNA (cpDNA) of the putative introgressive hybrids were identical to A. sikokianum from Kochi Prefecture and A. tosaense from Tokushima Prefecture. The results suggest that the plants are introgressive hybrids of A. sikokianum and A. tosaense and that they have highly exchanged genes with A. tosaense.

To describe the phylogeographic structures of Asparagus schoberioides Kunth (Asparagaceae) in Japan, we investigated its nucleotide sequence variations with respect to its geographic distribution pattern. Sequencing of the internal transcribed spacer (ITS) 1 region in 29 samples of A. schoberioides revealed 20 polymorphic nucleotide sites. As a result, the 29 samples of A. schoberioides fell into 15 distinct haplotypes and phylogenetic analyses revealed these haplotypes fell into two major clades, Clade 1 and Clade 2. The haplotypes of Clade 1 were distributed chiefly along the Pacific Ocean side of Japan, while those of Clade 2 occurred mainly along the Japan Sea side. This result suggests that A. schoberioides has migrated via two routes in Japan.

To determine the eVolutionary history of Asparagus cochinchinensis (Asparagaceae), we investigated the geographic pattern of its nucleotide sequence variations in Japan, Taiwan, South Korea and China. We found 21 polymorphic nucleotide sites by sequencing the internal transcribed spacer (ITS) region, which gave rise to a total of 15 haplotypes, labeled A to O. The A-type was found only in inland China (Guizhou and Sichuan), and the other haplotypes in China extended to several lineages; therefore, A. cochinchinensis may have its origin in the interior of China. The I-type has large distribution area and it also experienced a quick expansion in relative recent years. Haplotype differentiation was observed between the eastern and western side of the Central Mountain Ridge in Taiwan. Two lineages were found in Japan, one in the Yaeyama Islands and the other in remaining areas of Japan, implying that A. cochinchinensis independently colonized in Japan at least twice.

A morphologically intermediate plant between Arisaema sikokianum Franch. et Sav. and A. serratum (Thunb.) Schott has been newly found in Kochi Prefecture, Shikoku, Japan. The putative hybrid has the intermediate morphological characteristics of the parental species. Molecular analysis using PCR-RFLP of internal transcribed spacer (ITS) in nuclear DNA (nrDNA) indicates that the putative hybrid has a combined pattern of the two putative parent species. Moreover, the sequence result of chloroplast DNA (cpDNA) of the putative hybrid was identical to that of A. sikokianum. These results suggest that the putative hybrid is a hybrid between A. sikokianum and A. serratum and that it was formed by interactive gene exchanging via pollens from A. serratum to A. sikokianum. It is the first record of a hybrid between A. sikokianum and A. serratum.