Castanopsis sieboldii (Makino) Hatus. ex T.Yamaz. et Mashiba

Family: Fagaceae
Japanese: スダジイ [Sudajī]

More than any other, to me, this is the tree that represents the bounty of broad-leaf evergreen forests. They can grow to be absolutely massive, sometimes with multiple trunks from one stump, sometimes with one huge trunk. The acorn-like seeds can be eaten raw. Unfortunately, they are susceptible to fungus introduced into trunks by boring insects. Around 2014, many of the trees that came in naturally after logging died, but they are still abundant overall. There are a few gigantic specimens.

References:
新版　屋久島の植物 川原勝征,初島住彦(監修),2001：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14日）