This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 葼 is uncertain. It visually contains 艹 (grass) and 㚇, but the original semantic and phonetic roles are unclear.
The top grass radical 艹 suggests a plant, and the bottom 㚇 looks like a tangled cluster. Picture a small, tangled branch or twig sprouting from grass.
For ソウ, imagine a small twig (こえだ) growing in the soul of a dense forest: soul -> ソウ, and the twig is the kanji's shape.
slender shoot; scion; switch