Castanopsis sieboldii

{{Short description|Species of flowering plant}}

{{Speciesbox

|image = Castanopsis sieboldii2.jpg

|genus = Castanopsis

|species = sieboldii

|authority = (Makino) Hatus

|synonyms = Castanopsis cuspidata var. sieboldii (Makino) Nakai

Pasania cuspidata var. sieboldii Makino)

Shiia sieboldii Makino)

}}

Castanopsis sieboldii, also known as the Itajii chinkapin or Itajii, is a species of evergreen tree that lives in subtropical eastern Asia.{{cite web|url=http://shikigami.net/forest/shii-castanopsis-sieboldii/|title=Shii (Castanopsis sieboldii)|work=Thinking Like a Forest}}{{cite web|url=http://lifeinkochi.net/2012/08/a-japanese-useful-tree-castanopsis//|title=A Japanese useful tree: Castanopsis - Life in Kochi|work=Life in Kochi}}

This is a climax species that is commonly found in the Japanese temperate rainforest.{{cite web|url=http://scholarspace.manoa.hawaii.edu/handle/10125/22712|title=Canopy Multilayering and Woody Species Diversity of a Subtropical Evergreen Broadleaf Forest, Okinawa Island.|work=hawaii.edu}} Specimens are also present within the forest area of the Tokyo Imperial Palace.

Castanopsis sieboldii was once thought to be a subspecies of the similar Castanopsis cuspidata.

Plants and animals associated with this tree include:

• Aspidistra elatior, the cast-iron plant, grows in the understorey.
• Acrocercops mantica, Chrysocercops castanopsidis, and Lymantria albescens{{cite web|url=http://mothphotographersgroup.msstate.edu/species.php?hodges=19458|title=Moth Photographers Group – Lymantria albescens – 19458|work=msstate.edu}} larvae of these Asian moths likely mine the leaves.
• Amantis nawai, a small praying mantis species native to Eastern Asia is known to live around C. sieboldii where it eats insects.
• Okinawa rail, a Japanese bird, lives among these trees.