This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
杬 combines 木 (tree) with 元, but the exact historical development is uncertain. It may have originally referred to a type of tree or wood, but no clear meaning survives in modern Japanese.
A tree 木 beside a source 元 suggests a specific tree or wood, but its meaning is unclear. Imagine a mysterious tree whose name has been lost.
For ゲン, picture a genie emerging from the tree: genie -> ゲン, and the tree is the source of the magic.