What figure of speech is soaring weeping birches?

Answer 1

It is an oxymoron, that is, a literary device that includes terms that contradict each other. "Weeping" in horticulture means growing downward, and is frequently applied to willows, birches, and some ornamental fruit trees whose branches dramatically bend toward the ground. Therefore, "soaring," which implies upward flight, contrasts with the downward movement suggested by "weeping." The phrase creates a feeling that the birches are tall and sweeping upward, yet their branches are also being pulled toward the ground, as if the tree itself is indecisive.