This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 葘 is uncertain. It visually contains the grass radical 艹 over a component resembling 甾, but the origin and original meaning are unclear.
The top is grass 艹, and the lower part looks like a field 田 with extra strokes. Picture an overgrown, abandoned field: a wasteland.
For シ, imagine a sheep grazing in the overgrown wasteland: sheep -> シ, and the grass covers the field.