Mistletoe (Phoradendron flavescens)
Why we grow it: A parasitic plant that grows out in the wild, you might spot some in your yard using a black poplar, ash, sycamore, or hawthorn as a host tree. A bough of mistletoe, with its sticky, white berries, has long been used as a traditional decoration indoors during the Christmas season.
Deadly parts: All parts, especially the berries
Toxic toll: Munching on a couple of leaves, berries, or shoots—or drinking mistletoe-flavored tea—will cause abdominal pain and diarrhea. Cases where mistletoe ingestion were fatal involved gastroenteritis (an inflammation of the stomach and small intestine), followed by cardiovascular collapse. The berries are particularly potent when it comes to pets, so mind your cats and dogs around this plant.