Sorta Creepy VegetablesPlants generally make their own food through the process of photosynthesis. These plants are called autotrophs (self-feeding). However, some species have taken a different route for nourishment. These plants, called heterotrophs (other feeding), lack chlorophyll and cannot make their own food. Such plants can be recognized as lacking any green parts and are often succulent to some degree. The most common groups of plants that do this are some orchids and monotropes, which are a sub-group of the Heath family, Ericaceae. Ericaceae is a well known and diverse family including blueberries, rhododendrons, wintergreen and many others, which are quite different from the monotropes to the degree that some taxonomic treatments separate them out in their own family, Monotropaceae. Most of the monotropic plants in the North America occur in the west.
Based on how they obtain their food, there are two main categories of non-green, non-photosynthetic, heterotrophic plants.
The first group of plants is parasitic on other plants for their food. As parasites, they obtain their nourishment from a host green plant directly through the use of root structures called haustoria. Examples of such parasitic plants include the ground cone, squawroot and all members of the broomrape family, Orobanchaceae.
The second group includes the fungus feeding plants or mycotrophic plants. These plants utilize an intermediary mycorrhizal fungus that attaches to the roots of a green host plant, often a tree. This much larger group of non-green plants includes some orchids and the monotropes. Previously, mycotrophic plants were considered saprophytes or plants that derive their nutrients from decaying organic matter. The relationship between these plants and the soil fungi is now better understood. The plants tap into the fungus and receive water and nutrients that were shared between the fungus and tree. For this reason, this group of plants is often considered epiparasites. Some plants such as some members of the genus Pyrola generally have green leaves, but occasionally are leafless forms and thus heterotrophic.
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