the violet
菫 centers on the violet flower. The given meaning is simply 'the violet', referring to the plant itself.
菫 combines the grass radical 艹 with a phonetic component that historically represented the sound. The exact origin of the lower part is uncertain, but it likely contributed the reading while the grass radical indicates a plant.
The grass radical 艹 on top tells you it's a plant. Picture a delicate violet blooming among the grass.
For キン, imagine a violet pinned to a lapel: pin -> キン, and the violet is the flower being pinned.
violet (any flower of genus Viola, esp. the Fuji dawn, Viola mandshurica)
African violet
sweet violet (Viola odorata)
Viola eizanensis (flower in the violet family)
Viola vaginata (violet species)
cordierite
common butterwort (Pinguicula vulgaris)
Viola eizanensis (flower in the violet family)
Viola verecunda (violet species)
Viola sieboldii (violet species)