Origin

This character combines wood on the left with a component meaning "change" or "renew" on the right. The wood part indicates we are talking about a plant or wooden object, while the right component most likely functions as a sound hint for pronunciation rather than adding semantic meaning. The overall character came to mean "stem" or "stalk" of a plant because a stem is the woody part that holds up and supports the flower or fruit, and it may also have developed the sense of "blocked" or "stopped up" through association with something that obstructs or closes off, similar to how a stem can be rigid or blocking.