Hemiparasite

Most mistletoes are "hemiparasites." This means they don't rely on their hosts for all their needs: Instead, they harvest the sun's energy to make some sugars for themselves. Nonetheless, if you're a tree, you don't want to be festooned with them. Two or three shouldn't be a problem, but dozens of mistletoes can lead to water stress, insect infestation or even death.