Do trees leak?

Ok this is a question that has been bugging me for a while because here at Clemson there are a few trees that always have puddles underneath them. They are in between Daniel and Edwards. They line along the stairs that go down to the library bridge. And they a lot of times seem to be leaking, there are mysterious puddles and you can see water dripping down, on one occasion or two or more they would leak onto my head. I really need someone to explain to me why these trees leak????