Willows do have a reputation of helping other plants root.
I have lots of pussy willows in some wetlands and gave away a bunch shortly before Easter. I kept a few pussy willow cuttings in some containers and wanted to see how well they put out roots. I drained off some of the water and used it when I planted some rooted cutting trees that I received from the Arbor Foundation. When the trees arrived, they were in pretty sorry shape. What can I tell you, I planted the little trees and they took off like gang busters.