I have heard that willow is like aspirin.
Before it came down, there was a neighbor's weeping willow that hung over the fence. I made a daylily bed in that area and always kept the dropped fall leaves in the bed hoping that they would help with growth.
I think after years, that they did. However it is also a 'hot' area, and the ground is never stepped on and the beds were made with compost. So who knows?
I like old truthful 'wise' tales!
