Metanarthecium

Metanarthecium is a genus of monocotyledonous flowering plants native to eastern Asia. Its only known species is Metanarthecium luteoviride, known from Japan, Korea, and the Kuril Islands.
Two varieties are recognized:

Metanarthecium luteoviride var. luteoviride - Japan, Korea, and the Kuril Islands
Metanarthecium luteoviride var. nutans Masam. - Yakushima