lush vegetation, luxuriant growth
蒨 centers on abundant, thriving plant life: lush vegetation and luxuriant growth.
蒨 combines the grass radical 艹 with 倩, which likely contributes the sound and may relate to beautiful or flourishing growth. The exact historical development is uncertain.
The grass radical 艹 sits above 倩, like a beautiful, lush meadow growing over everything. Picture a field so thick with plants that it looks luxuriant and healthy.
For セン, imagine a thousand (千, せん) tiny sprouts pushing through the soil, creating a scene of lush vegetation: 千 -> セン, and the field becomes thick with growth.