oak
楢 centers on a specific type of tree: the oak. Its meaning is straightforward and refers to the oak tree itself.
楢 combines 木 (tree) with 酋, which likely contributes the sound. The character was created to represent the oak tree specifically.
The left side 木 means tree, and the right side 酋 looks like a chief with a headdress. Picture a mighty oak tree standing like a chief among the forest.
For シュウ, imagine a shoe hanging from an oak branch: shoe -> シュウ, and the oak tree holds it up.
oak (esp. Quercus serrata)
konara oak (Quercus serrata); pin oak
Mongolian oak (Quercus mongolica)
English oak (Quercus robur); pedunculate oak; common oak; French oak
Narayama Bushikō - The Ballad of Narayama (1954 novel by Fukazawa Shichirō, 1983 film by Imamura Shōhei)
honey fungus (Armillaria mellea); honey mushroom
English oak (Quercus robur); pedunculate oak; common oak; French oak