What does "purple" refer to in Emily Dickinson's poem "Where ships of purple - ; gently toss"? What is the meaning of ships here?what does purple...

Emily Dickinson’s poetry has always been rife with
metaphors and imagery, and “Where ships of purple gently toss” is a great example.  The
“ships” have been interpreted as flowers in a garden and also as clouds in the sky. 
Laurence Perrine, in his essay “The Nature of Proof in the Interpretation of Poetry,”
believes that the “ships” are more of a reference to clouds, because some of the words
that Dickinson uses don’t work as well with the image of a
garden.

Instead of saying “daffodils,” which would work for
the garden imagery, she uses only the singular “daffodil,” which suggests the color
instead.  The “wharf” also doesn’t work well with the scene of a garden, but it could
work with the scene of clouds going by in the sunset, rich with color and the images
that we all can make up in the clouds we see.  Once the wind stops, though, the “wharf”
or sky, is still.