Hosta sieboldiana (Hook.) Engl. var. sieboldiana

Family: Asparagaceae
English: Hosta (sp.), Plantain lily, blue-leaved Hosta (sp)
Japanese: オオバギボウシ [Ōbagibōshi] or トウギボウシ [Tōgibōshi]

Prized for their beautiful foliage, Hostas are common sites in gardens around the world, and this species has particularly large [Tōgibōshi] leaves. However, these leaves are also prized by deer, and Hostas have waned as the deer population has waxed in recent years in Yakushima. Now they are restricted mostly to gardens and outcroppings in riverside cliffs. I used a harness and self-belay system to catch these.

References:
屋久島の植物 川原勝征,初島住彦(監修),1995：南方新社.
米倉浩司・梶田忠 (2003-)　「BG Plants 和名－学名インデックス」（YList），http://ylist.info（ 2019年8月13日