ilex, holm oak, birdlime tree
檍 centers on a specific type of tree: the ilex or holm oak, also known as the birdlime tree. The meanings all point to the same tree species.
檍 combines 木 (tree) with 意, which likely contributes the sound オク. The character was created to name a specific tree, the ilex or birdlime tree.
The left side 木 is a tree, and the right side 意 suggests the idea of 'mind' or 'thought'. Picture a thoughtful tree that produces sticky birdlime, like the ilex, as if it has a clever plan.
For オク, imagine an oak tree that is actually an ilex: oak -> オク, and the tree's sticky birdlime catches birds like a clever trap.