There are certain plants in nature which do not have chlorophyll and hence cannot produce their own food. These plants uses heterotrophic mode of nutrition to derive food for their survival. In a heterotrophic mode of nutrition, organisms directly or indirectly depend on autotrophs for food. Organisms which show this mode of nutrition are called Heterotrophs, as they cannot prepare their own food.
Heterotrophs: Organism that cannot produce its own food by carbon fixation, but derives nutrition from other sources of organic carbon, mainly plant or animal matter.
There are two major heterotrophs:
  • Parasites and
  • Saprophytes
Parasitic nutrition: In this mode, the organism lives inside or outside the body of another organism. Such organisms are called parasites.  Parasites take nutrition from the other organism and sometimes may even kill the organism in which they live.
Parasitic plants: A parasitic plant is a plant that derives some or all of its nutritional requirement from another living plant.
Cuscuta (Amarbel) is a yellow tubular plant twisting around the stem and branches of a tree. It does not have chlorophyll and hence cannot make its own food. They climb on other trees known as host plant and absorb the readymade food. Therefore plants like Cuscuta are known as parasite.
Saprophytic mode of nutrition: Microorganisms like fungi use another mode of nutrition
known as saprotrophic mode of nutrition. The organisms undergoing this mode of nutrition are known as saprophytes.
Generally saprophytes feeds on a decomposing matter from dead organisms.
These fungal spores are present in air and grow as dark patches on the food items or other items like pickles, leather and clothes during hot, humid or rainy season.They sit on dead and decaying matter where they germinate and grow.
Some other species of plants known as insectivorous plants are capable of trapping insects and digesting them. These plants are known as pitcher plants with its leaf modified as pitcher.
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At top of the leaf forms a cover which closes or opens the mouth of the modified leaf. The pitcher consists of hair like projections directed downwards. As soon as an insect lands over the pitcher the cover of the pitcher opens to swallow the insect. As the insect gets inside the pitcher the top closes and the insect gets knotted in the hair. The plant then digests the insect with the help of the digestive juices secreted inside the pitcher.