This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
棈 combines 木 (tree) with 青, which likely contributes the sound. The exact historical development and original meaning are uncertain.
The kanji visually combines tree 木 and blue/green 青. Without a known meaning, you might picture a rare blue-green tree, but this is only a mnemonic placeholder.
For セン, imagine a centipede crawling up the blue-green tree: cent -> セン, tying the sound to the visual shape.
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Chinese cork oak (Quercus variabilis)