salt marsh plant
芩 refers to a specific salt marsh plant. Its meaning is narrow and botanical, with no clear broader conceptual center beyond that plant.
芩 combines the grass radical 艹 with 今, which likely acts as a phonetic component. The character is used for a specific plant name, but the exact historical development is uncertain.
The grass radical 艹 sits above 今, like a plant growing in the present moment. Picture a salt marsh plant sprouting right now: 今 (now) under 艹 (grass) gives the plant 芩.
For キン, imagine a king (キン) inspecting a rare salt marsh plant: the king's visit makes the plant feel important. King -> キン.