flag, banner
籏 centers on a flag or banner, a piece of cloth used as a symbol or signal.
籏 is a variant form of 旗, adding the bamboo radical 竹 on top. The exact historical development is uncertain, but it likely arose as a specialized or decorative variant.
Imagine a bamboo pole (竹) holding up a flag (旗): together they make 籏, a flag on a pole.
For キ, picture a key tied to the flag: key -> キ, and the key unlocks the banner's message.