The parasitic mode of existence is frequently encountered among all life forms, including flowering plants. In this discussion a plant will be considered parasitic only if it produces a haustorium, the modified root that forms the morphological and physiological link to another plant (the host). Some plants, such as the ghostly white Indian Pipe (Monotropa) are often called parasites, but are more properly termed mycotrophs (Greek mykes, meaning "fungus," and trophos, meaning "feeder"). Mycotrophs, which occur in many plant families, lack chlorophyll and are nonphotosynthetic, and their