Saprophytic Plants The other type of plants that don't use CO2 are the saprophytic plants. These are also not green, can't do photosynthesis, and therefore, also cannot use CO2. These guys are not parasites though. They are more like fungus, in that they live off dead inorganic matter. Fungus and saprophytes often live together and apparently help each other. The fungus helps the saprophytes by excreting digestive enzymes that help the saprophyte "eat" its food, and the saprophytes somehow provide carbohydrates to the fungus.