Like his use of meter, Kilmer’s use of rhyme is very conventional. The poem consists entirely of rhyming couplets, where each of the rhymes is exact and occurs precisely on the final stress of each line. When Kilmer composed “Trees” in 1913, he did so at a time when many of his contemporaries were growing tired with the conventions of verse handed down from previous centuries. Such poets began to experiment with abandoning the use of regular meter and rhyme. For these writers, the resistance to—and even abandonment of—traditional features of verse was closely linked to their diminishing faith in the authority of many social, political, and religious institutions. By contrast, Kilmer was a devout Catholic who retained his faith in the moral and spiritual authority of his religion. As such, he chose to center simplicity as a way to reflect the harmony and balance of God’s Creation. Hence, the rhymes in this poem are all quite straightforward, endowing the verse a “poetic” quality that doesn’t detract from the speaker’s message of devotion.

In addition to evoking an overall impression of harmonious balance, Kilmer also uses rhyme to meaningful effect, and particularly in the final couplet (lines 11–12):

     Poems are made by fools like me,
     But only God can make a tree.

To see why the rhyme between “me” and “tree” is significant, recall the first couplet’s claim that no poem will ever be as lovely as a tree. The speaker then spends four couplets explaining why trees are especially lovely, before ending with this couplet. It is only at this point in the poem that it becomes clear—both to the speaker and the reader—that it may in fact be absurd to compare a poem to a tree. Doing so would imply a further comparison between the writer of the poem and the creator of the tree. However, as the speaker recognizes here, it’s absurd to compare “fools like me” to “God,” who alone can make a tree. Yet at the same time as the speaker recognizes this absurdity, they also rhyme “me” and “tree,” which points to what is ultimately the more appropriate comparison. Instead of comparing themself as a creator of verse to God the Creator of everything, it would be more suitable for the speaker to compare themself to a tree. After all, they are both God’s creations.