Which

Hello....

I'd like to know what the underlined "which" refers to.

I am not looking for some correct answers in English Literature...

I am only looking for native speaker's sense of English before mcuh thinking..

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For Daisy was young and her artificial world was redolent of orchids and pleasant, cheerful snobbery and orchestras which set the rhythm of the year, summing up the sadness and suggestiveness of life in new tunes. All night the saxophones wailed the hopeless comment of the "Beale Street Blues." while a hundred pairs of golden and silver slippers shuffled the shining dust. At the gray tea hour there were always rooms that throbbed incessantly with this low, sweet fever, while fresh faces drifted here and there like rose petals blown by the sad horns around the floor.