broom
菷 centers on a broom: a tool for sweeping and cleaning.
菷 combines 艹 (grass) with 帚 (broom), suggesting a broom made of grass or plant material. The exact historical development is uncertain.
The top 艹 is grass, and the bottom 帚 looks like a hand holding a broom. Imagine tying grass together to make a simple broom.
For シュウ, picture a shoe sweeping the floor like a broom: shoe -> シュウ, and the shoe acts as a makeshift broom.