Arisaema longipedunculatum

Family: Araceae
Japanese: ヤクシマヒロ(ノ)ハテンナンショウ (Yakushima Hiro-ha ()no) Tennanshou)

This species of "wide-leaf" arisaema is considered endangered and the yakushima variety--with limited-- range is critically endangered. The flowers look very similar to the much more common A. serratum, but the leaves are broader and fewer.

References:
屋久島高地の植物 川原 勝征,2001:南方新社.
Tropicos.org. Missouri Botanical Garden. 05 Jun 2013 http://www.tropicos.org/Name/2106636 from Serizawa, Shunsuke. Acta Phytotaxonomica et Geobotanica 32(1-4): 27. 1981.
米倉浩司・梶田忠 (2003-)　「BG Plants 和名－学名インデックス」（YList），http://bean.bio.chiba-u.jp/bgplants/ylist_main.html（2014年6月2日）.