artemisia stelleriana
蔞 refers specifically to Artemisia stelleriana, a plant in the mugwort family. Its meaning is a single botanical name rather than a broad conceptual idea.
蔞 combines the plant radical 艹 with 婁, which likely provides the sound. The character was created to name a specific plant, Artemisia stelleriana.
The plant top 艹 sits above 婁, which looks like a woman 女 beside a mouth 口 under a roof. Picture a woman gathering this specific mugwort-like plant and naming it after the sound 婁.
For ロウ, imagine a low-growing Artemisia plant: low -> ロウ, and the plant stays close to the ground.
vernal water-starwort (Callitriche palustris)