Mistletoe

"...both European Mistletoe and the North American species, Phoradendron serotinum, are commercially harvested for Christmas decorations. Mistletoe plants grow on a wide range of host trees, and commonly reduce their growth but can kill them with heavy infestation. Viscum album can parasitise more than 200 tree and shrub species. All mistletoes are hemi-parasites, bearing evergreen leaves that do some photosynthesis, and using the host mainly for water and mineral nutrients. Mistletoe first sprouts from bird feces on the trunk of the tree and in its early stages of life it takes nutrients from this source. Most mistletoe seeds are spread by birds" - Wikipedia