But while other eminent poets of his generation became widely known for social activism (Adrienne Rich and Gary Snyder, for example) or forays into fiction (James Dickey) or the details of their own harrowing lives (Sylvia Plath), Mr. Ashbery was known primarily for one thing: writing poetry. (You can read some of it here.)

That poetry is by turns playful and elegiac, absurd and exquisite — but more than anything else, it is immediately recognizable. If some poets remind us of the richness of American poetry by blending seamlessly into one of its many traditions, Mr. Ashbery has frequently seemed like a tradition unto himself. It is a cliché to praise a writer by saying no one has ever sounded quite like him, and yet: No one has ever sounded quite like him.

Not that they have not tried. Charles McGrath, the editor of The New York Times Book Review from 1995 to 2004, recalled that a large portion of new poetry titles during his tenure could be (and often were) tossed into a pile labeled “Ashbery impersonations.” And Mr. Ashbery remains far and away the most imitated American poet.

That widespread imitation has served mostly to underscore the distinctive qualities of the original — and those qualities are singular indeed. An Ashbery poem cycles through changes in diction, register and tone with bewildering yet expertly managed speed, happily mixing references and obscuring antecedents in the service of capturing what Mr. Ashbery called “the experience of experience.”

The effect can be puzzling, entrancing or, more frequently, a combination of the two — as if one were simultaneously being addressed by an oracle, a PTA newsletter and a restless sleep talker. The beginning of Mr. Ashbery’s 1974 poem “Grand Galop” is representative of his approach:

All things seem mention of themselves

And the names which stem from them branch out to other referents.

Hugely, spring exists again. The weigela does its dusty thing