The section of the poem where the "sleeping flowers" appears is a point where Wordsworth employs a series of natural images that are designed to bring to light all of what is being missed when one fails to communicate with the natural world.  As individuals have sacrificed their own sense of communion and connection to nature, they have also forgone a sense of linking to this world and, in the process, have lost sight of all that is important and precious within the setting.  For example, the result of the "sordid boon" is being able to not recognize the sea, "that bares her bosom to the moon" and the howling winds.  The notion of "sleeping flowers" is one such image that helps individuals become aware of what has been missed out when one succumbs to a conformed materialist view where individuals seek to forgo their connection with the natural world.