The speaker addresses dead trees, asking a hard question: who flowers in death? It's half taunt, half plea. The speaker wants the trees to give up their secrets, imagining them carved into bark and bleeding a strange, bloody sap. The trees become almost human, wounded and forced to confess.
In the second stanza the speaker moves from watching to taking part. When the cold strips the petals away, they will be gathered in the speaker's ears and mouth, then turned into a "vomit mosaic," bright and vivid, until only the smell of rot is left. The speaker seems to want to swallow and absorb the trees' death, then give it back as something ugly and beautiful at once.
The mood is morbid, intimate, and a little hungry. The title places the scene in Oklahoma, but the poem doesn't explain why the trees are dead. What it leaves is a sense of grief mixed with fascination, as if the speaker can't look away from decay.