Study of native Hosta species on Shikoku Island, Japan^©

Hostas are perennial herbs native to eastern Asia including Japan, Korea, and China. About 20 species are recorded in Japan now. There are about 12 Hosta species on Shikoku Island. Eleven species are recorded just for Kochi Prefecture, among 13 species on Shikoku Island, including: H. alismifolia (baran-giboushi), H. capitata [syn. H. nakaiana (kanzashi giboushi)], H. sieboldiana var. montana [syn. H. montana (ohba giboushi)], H. sieboldii (koba giboushi), H. longissima (mizu giboushi), H. longipes [syn. H. longipes var. caduca (saikoku iwa giboushi)], H. gracillima [syn. H. longipes var. gracillima (hime iwa giboushi)], H. kikutii var. polyneuron (sudare giboushi), H. kikutii var. caput-avis (unazuki giboushi), H. kikutii var. tosana (tosano giboushi), and H. tardiva (nankai giboushi). Hostas are used as garden plants, materials for flower arrangements, and for vegetables. Hosta plants are known as a vitamin C rich vegetable in Japan with H. tardiva a popular vegetable with slight bitterness in Kochi, Shikoku. However, in Europe and America hostas are used as garden plants with very high popularity for a long time. Philipp F. B. von Siebold introduced Japanese hosta cultivars to Europa at the end of 17^th century.