In fact, it looks like we need to be more specific; put actually needs a PP which describes a location. But having said that, it's not clear that we need to say that this complement of put needs to be a PP at all. Perhaps if we just say that one of put's complements is a location, the fact that it's a PP will follow; the semantics might be able to tell us that locations can be realized syntactically as PPs but not, for example, as VPs, or NPs.