creepers, trailing plants, vines
葎 centers on plants that spread by creeping or trailing: vines, creepers, and similar climbing or ground-covering plants.
葎 combines the grass radical 艹 with 律, which likely contributes a phonetic element. The exact historical development is uncertain, but the structure suggests a plant name.
The grass top 艹 covers 律, like vines creeping over a rule or pattern. Picture a measuring stick overgrown with trailing plants.
For リツ, imagine a vine that grows in neat rhythms, like a musical beat: rhythm -> リツ, and the vine follows the rhythm as it creeps.