Question: The most famous and often parodied poem by Joyce Kilmer was written in what verse structure?

Context paragraphs:
Joyce Kilmer Memorial Forest: Joyce Kilmer Memorial Forest is an approximately 3,800-acre tract of publicly owned virgin forest in Graham County, North Carolina, named in memory of poet Joyce Kilmer (1886–1918), best known for his poem "Trees".  One of the largest contiguous tracts of old growth forest in the Eastern United States, the area is administered by the U. S. Forest Service.  The memorial forest is a popular family hiking destination and features an easy two-mile, figure-eight trail that includes a memorial plaque at the juncture of the two loops.  In 1975 the memorial forest was joined with a much larger tract of the Nantahala National Forest to become part of the Joyce Kilmer-Slickrock Wilderness.

Amoebaean singing: Amoebaean singing is a type of singing competition originating in Ancient Greece.  In it, a first party sings according to a topic and verse structure of their choosing.  A second singer then responds with the same verse structure and on a related topic.  This repeats until one side concedes or a third party can determine the winner.

Symmetry in the Quran: Symmetry in the Quran is the belief held by some Muslims, that the word and verse structure of the Quran exhibits such complicated symmetry that it could be neither random placements, nor the intentional work of man, but rather proof of "the will of God".  There are many examples of such symmetry.  Using a program called QuranCode and other analysis programs, scholars have found many patterns.  An example is that chapter 76, called Al-Insan, has 247 words.  It has three mentions of the word silver.  The middle word of the chapter is word number 124.  It is the word silver.  It is in a verse that is the middle verse of the chapter (verse 16 of 31).  It is the third of five words of the verse.

Hudibrastic: Hudibrastic is a type of English verse named for Samuel Butler's "Hudibras", published in parts from 1663 to 1678.  For the poem, Butler invented a mock-heroic verse structure.  Instead of pentameter, the lines were written in iambic tetrameter.  The rhyme scheme is the same as in heroic verse (aa, bb, cc, dd, etc.), but Butler used frequent feminine rhyme for humor.

Joyce Kilmer: Joyce Kilmer (born as Alfred Joyce Kilmer; December 6, 1886 – July 30, 1918) was an American writer and poet mainly remembered for a short poem titled "Trees" (1913), which was published in the collection "Trees and Other Poems" in 1914.  Though a prolific poet whose works celebrated the common beauty of the natural world as well as his Roman Catholic religious faith, Kilmer was also a journalist, literary critic, lecturer, and editor.  While most of his works are largely unknown, a select few of his poems remain popular and are published frequently in anthologies.  Several critics—including both Kilmer's contemporaries and modern scholars—have disparaged Kilmer's work as being too simple and overly sentimental, and suggested that his style was far too traditional, even archaic.  Many writers, including notably Ogden Nash, have parodied Kilmer's work and style—as attested by the many parodies of "Trees".

Trees (poem): "Trees" is a lyric poem by American poet Joyce Kilmer.  Written in February 1913, it was first published in "Poetry: A Magazine of Verse" that August and included in Kilmer's 1914 collection "Trees and Other Poems".  The poem, in twelve lines of rhyming couplets of iambic tetrameter verse, describes what Kilmer perceives as the inability of art created by humankind to replicate the beauty achieved by nature.

Cumulative song: A cumulative song is a song with a simple verse structure modified by progressive addition so that each verse is longer than the verse before.  Cumulative songs are popular for group singing, in part because they require relatively little memorization of lyrics, and because remembering the previous verse to concatenate it to form the current verse can become a kind of game.

Rouge Bouquet (poem): "Rouge Bouquet" or "The Wood Called Rouge Bouquet" is a lyric poem written in 1918 by American poet, essayist, critic and soldier Joyce Kilmer (1886-1918).  The poem commemorates during an intense German artillery bombardment of an American trench position in the Rouge Bouquet wood near the French village of Baccarat on 7 March 1918 that resulted in the loss of 19 American soldiers with the 165th Infantry Division.  Kilmer was a sergeant in the New York National Guard's "The Fighting 69th Regiment" which was part of the 165th Infantry Regiment involved in the attack.  Kilmer composed the poem immediately after the bombardment, and it was first read over their graves in March 1918.  The poem was first published two weeks after Kilmer's death in battle on 30 July 1918 during the Second Battle of the Marne in the 16 August 1918 issue of "Stars and Stripes".  The poem was read over Kilmer's own grave when he was interred in France.  To this day, it is a tradition of the Fighting 69th to read the poem at memorial services for fallen members of the regiment.

Joyce Kilmer Middle School: Joyce Kilmer Middle School is a school in the Fairfax County Public Schools System in unincorporated Fairfax County, Virginia, United States, east of the city of Vienna.  Kilmer serves grades 7-8.  It was named after the journalist and poet Joyce Kilmer.  Kilmer has a GT program for students who have been determined to be "Gifted and Talented."  It is now called AAP, or "Advanced Academics Program."

69th Infantry Regiment (New York): The 69th Infantry Regiment is an infantry regiment of the United States Army.  It is from New York City, part of the New York Army National Guard.  It is known as the "Fighting Sixty-Ninth", a name said to have been given by Robert E. Lee during the Civil War.  An Irish heritage unit, as the citation from poet Joyce Kilmer illustrates, this unit is also nicknamed the "Fighting Irish", immortalized in Joyce Kilmer's poem "When the 69th Comes Home".  Between 1917 and 1992 it was also designated as the 165th Infantry Regiment.  It is headquartered at the 69th Regiment Armory in Manhattan.

Supporting paragraphs: Trees (poem) Joyce Kilmer
Answer: iambic tetrameter