Even though mistletoes parasitize host trees, most species have green leaves and carry out photosynthesis, normally only taking water and minerals from the host. They are therefore only partial or hemi-parasites. Pictured is the European mistletoe (Viscum album) that has a long history of use in folk medicine from the time of the Druids. The medicinal and magical properties of mistletoe may not be due entirely to superstitious beliefs—there is some evidence that mistletoe extracts have some anti-tumor effects—but beware: the white berries can be toxic to pets and humans. In North America, the native mistletoe species is Phoradendron leucarpum, whose berries also have toxicity, causing intestinal irritation and lowered blood pressure.
Ted Kinsman, College of Imaging Arts and Sciences, Rochester Institute of Technology, NY.