Introgressive Hybrids of Arisaema sikokianum and A. tosaense (Araceae) Confirmed through Nuclear and Chloroplast DNA Comparisons

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.