hemp palm
棕 refers to the hemp palm, a type of palm tree whose fibers are used like hemp.
棕 combines 木 (tree) with 宗, which likely provides the sound. Together they indicate a type of palm tree.
A tree 木 with a religious sect 宗: imagine a palm tree used in temple ceremonies, its fibers woven into sacred ropes.
For シュ, picture a shoe made of hemp palm fibers: shoe -> シュ, and the shoe is woven from the palm tree.
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