hemiparasite

noun

1. Any parasitic plant that obtains energy by photosynthesis as well as from its host

   “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.”