Douglas Goetsch wrote Smell and Envy in the voice of a city poet scoffing at the nature poets, who think that because of where they live and what they're surrounded by, they have some sort of monopoly on the poetic.
so it blooms and withers only for you,
so all you have to do is name it: primrose
- and now you're writing poetry...
I like the suggestion here that there's a poetry just in the sound of words - like primrose - and there are many words from nature that lend themselves to this poetry. And that it's not just the poets of nature and countryside who can take those words and make poetry out of them. Though in the mind of a city poet the words take on a new form:
we dunk your roses in vats of blue
There's also a suggestion of laziness - that all a nature poet has to do is look out the window and there's the poem, right there, ready to be plucked from a tree. While a city poet has to wring a poem out of concrete.
And it's not only nature words that have poetry to them. There are urban words with poetry and music in them too, though maybe those words lend themselves only to a harsher kind of poetry (is there a word associated with city life that's comparable to, say, primrose? There might be, but it's likely more difficult to find).
As the poem continues there's also an implication of city poets being more knowledgeable about human nature (likely in a more cynical, wordly wise, "seen everything" sort of way). Not that a nature poet can't capture human character as well. Maybe it's that city poets get at the grittier parts of human nature and the greater varieties and idiosyncrasies (and downright insanity) of human personality - they can't help it; in a city everyone's crowded together. No one's flaws go unnoticed. You're nose to nose with a stranger in the subway and the wart on his chin is right at your eye level.
Maybe another contrast is that poems of nature capture the roots and foundations of human character, because we all once lived in nature; the truths of those poems seem to echo in your bones. With the city there's more a sense of displacement, distortion and dysfunctionality - maybe it's a poetry of feeling uncomfortable in your own skin. The Pleiades aren't the remote wonders of the starry night, when you're in the city:
When the moon is full
we hear it in the sirens. The Pleiades
you could probably buy downtown.
But nature can give you grittiness too, and the knots and intricacies of humanity. And maybe there are some lovely (possibly deeply resonant or maybe just uncomplicated) poems set amidst urban life; you know, the beauty of buildings, of city parks (oops, there's nature encroaching a little), and people standing out strikingly on a street corner.