Taxonomic Studies of Cirsium (Asteraceae) in Japan XII. Subsect. Nipponensia, Subsect. Nov. and a New Species, C. hachimantaiense, Belonging to the New Subsection

摘要

A new species of Cirsium, C. hachimantaiense Kadota, is described from Mt. Hachimantai, located at the border area among Akita, Aomori and Iwate Prefectures, northern Japan. Cirsium hachimantaiense is characterized by the presence of basal leaves at anthesis, nodding large capitula, bowl-shaped and exceedingly glutinous 7-8-seriate involucres and corolla tubes almost as long as throats. Based on these attributes C. hachimantaiense belongs to subsect. Schantarensia (Kitam.) Kadota [=ser. Schantarensia Kitam.]. However, the type species of the subsection, C. schantarense Trautv. & C. A. Mey., has not basal leaves at anthesis. A new subsection, subsect. Nipponensia Kadota, is therefore proposed for the other species of the former sub-sect. Schantarensia except for C. schantarense. Subsect. Nipponensia is consisted of at least eight species and is distributed in Japan (northern to western Honshu) and Taiwan.