What does bow their branches at a wish mean from the poem queen mab?

In the poem "Queen Mab" by Percy Bysshe Shelley, the line "Bow their branches at a wish" refers to how nature and the elements, like trees, bend and yield to the various desires of powerful entities, in this case, Queen Mab, who symbolizes fantasy and imagination. It suggests the idea that even the natural world can be influenced and manipulated by supernatural beings like Queen Mab.