Why does the speaker call the loveliest of tree?

In the poem "Loveliest of Trees, the Cherry Now," the speaker refers to the cherry tree as the "loveliest" due to its stunning beauty and the transient nature of its blossoms. The cherry tree symbolizes the fleeting moments of life, particularly the beauty of youth and springtime. The speaker's admiration reflects a deep appreciation for nature's beauty and a poignant awareness of life's impermanence. This evokes a sense of urgency to enjoy and cherish these moments before they fade away.