oak
橿 centers on a type of oak tree, specifically the Japanese evergreen oak (Quercus acuta) or a similar species. The meaning is a specific tree name rather than a broad concept.
橿 combines 木 (tree) with 畺, which likely contributes the sound. The character was created to name a specific type of oak tree.
The left side is a tree 木, and the right side 畺 looks like stacked fields. Picture a sturdy oak tree growing beside layered rice fields, its wood used for tools.
For キョウ, imagine a strong oak tree in Kyoto (キョウト): the first part of Kyoto cues キョウ, and the tree is a famous landmark.