A saprophyte is an organism that survives by consuming nutrients from dead and decaying plant and animal material, that is, organic matter. Saprophytes include fungi, molds, most bacteria, actinomycetes, and a few plants and animals. Saprophytes contain no chlorophyll and are, therefore, unable to produce food through photosynthesis, the conversion of chemical compounds into energy when light is present. Organisms that do not produce their own food, heterotrophs, obtain nutrients from surrounding sources, living or dead. For saprophytes, the source is non-living organic matter. Saprophytes are known as decomposers. They absorb nutrients from forest floor material, reducing complex compounds in organic material into components useful to themselves, plants, and other microorganisms. For example, lignin, one of three major materials found in plant cell walls, is not digestible by plant-eating animals or useable by plants unless broken down into its various components, mainly complex sugars. Certain saprophytic fungi are able to reduce lignin into useful compounds. Saprophytes thrive in moist, temperate to tropical environments. Most require oxygen to live. North American plant saprophytes include truffles, Indian Pipe (Monotropa uniflora), pinedrops (Pterospora andromedea), and snow orchid (Cephalanthera austinae), all of which feed on forest floor litter in the northeast forests.