This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 茊 is uncertain. It visually combines 艹 (grass) and 丘 (hill), but the original meaning and component relationship are unclear.
Grass 艹 growing on a hill 丘 suggests a place name or a plant, but the exact meaning is unclear.
For シ, imagine a single blade of grass on a hill, whispering 'she' in the wind: she -> シ.