This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 茼 is uncertain. It visually combines the grass radical 艹 with 同, but the original semantic and phonetic roles are unclear.
The grass radical 艹 over 同 suggests a plant, but the specific meaning is unclear. Think of it as a mysterious plant whose name you don't know.
For トウ, imagine a toe-shaped plant growing under the grass: toe -> トウ, and the plant is the mysterious 茼.