As in some of the poems of Whitman, a predominantly natural description enlists humanizing metaphorical elements. Is a woman's body actually "present" in the scene described?
I would say that the structure of the fantasm helps to resolve this question. The body of the beloved is invoked as a term of comparison. The field of Queen Anne's lace is thus charged with this association, though it takes on imaginal qualities that are partly natural, partly human—in short, an invention, a device for the speaker's purposes. The metaphor of the flower as "a hand's span / of her whiteness" likewise introduces the association of a hand with the lover caressing the woman's body, "Wherever / his hand has lain . . ." The shimmering quality of the field of flowers is gradually transformed into a woman's body tingling with sexual pleasure: "under his touch / to which the fibres of her being / stem one by one . . ." This metaphorical union is carried to its highest point: "until the whole field is a / white desire . . ." And then an emptying out occurs. Yes, the world can be imagined as the realm of the poet's desire—but what is really there has no more substance than a fleeting image. This is what I take Williams to be saying. This poem, then, is a sort of map or guide in the study of desire as a structuring force. We see here the relational qualities inherent in a poetic practice both engaged with the world and open to impulses stemming from the deepest regions of the psyche.
From Modern Poetic Practice: Structure and Genesis. New York: Peter Lang, 1986.