spinach
薐 refers specifically to spinach, a leafy green vegetable.
薐 combines the grass radical 艹 with 稜, which likely provides the sound. The character was created to represent spinach, a plant.
The grass radical 艹 sits above 稜, like spinach leaves growing from a ridged field. Picture a spinach plant with its leaves spreading out from the top.
For ロウ, imagine a row of spinach plants growing in a garden: row -> ロウ, and the spinach leaves form a neat row.