Mistletoe is a parasite. Some people say it harms trees, others say not so much. Opinions vary and I imagine it has a lot to do with climate.
I don’t think I’ve ever seen mistletoe grow on anything but oak trees, but the American mistletoe also grows on poplar, maple, tupelo, apple and thorn trees. Grapevines and apricot trees that grow in the Himalayas, are sometimes found with mistletoe growing on them.
What really surprised me was the way the mistletoe gets its start. Birds are attracted to the mistletoe berries and after they eat them, they clean their beaks while sitting on a tree branch. Because the berries are sticky, the seeds from the berries attach to the branch. Eventually, the seeds germinate and the mistletoe begins to grow. The roots grow right into the bark of the tree drawing water and nutrients. This parasitic action can cause the tree branch to die and lead to the death of the whole tree.
Suellen Ocean is the author of Acorns and Eat’em, a how-to vegetarian cookbook and field guide for eating acorns. Find it here: http://www.amazon.com/Acorns-Eatem-How–Vegetarian-Cookbook/dp/1491288973