This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
檰 combines 木 (tree) with 綿 (cotton), likely indicating a tree related to cotton or a fibrous material. The exact historical development is uncertain.
A tree 木 that produces something like cotton 綿: imagine a tree with fluffy cotton-like fibers.
For ヘン, picture a hen pecking at the cotton-like fibers on the tree: hen -> ヘン.