Do you know that there are certain plants which cannot produce their own food because of the absence of chlorophyll? Such plants, therefore, depend on other plants or dead animals for their food.
Plants which feed on dead organic matter are called ‘saprophytes’ and those which feed on plants are called ‘parasites’. Saprophytes play an important role in the decay process. They clear the land of dead animals by digesting and absorbing nutrients from the dead material. For instance, all fungi and bacteria which do not contain chlorophyll fall in this group.
Parasitic plants feed on other plants. They obtain water and food from the host through specially developed organs called ‘haustoria’ which secure the parasite to the host and grow into the host’s tissue. Parasitic plants do not give any benefit to their hosts in anyway. In some cases, they cause harm to their hosts.
The extent to which a parasite is dependent on its host largely determines its vegetative form. True parasites such as dodders, cuscuta and cassytha are entirely devoid of chlorophyll and rely entirely on the host as a food source. The dodder, which is a well-known parasitic plant, looks like a tiny slender snake. Its colour varies from bright yellow to red. When a dodder seed germinates, the young plant begins to grow in a circular fashion, searching for the mother plant. Once it gets a host, the thin stem of this plant twines around the host’s stem and starts taking food from the host.
Other parasites such as the toothwort and the broom are parasitic on the roots of other plants, rather than their stems. Correspondingly, these plants are less conspicuous than dodders because their vegetative parts are underground.
A well-known example of a partial parasite is mistletoe which grows as a cluster of branches hanging from trees. It produces a haustorium which connects with the host’s stem and extracts water and mineral nutrients. It can produce food by photosynthesis but needs water and minerals from trees.
Mosses and lichen are also parasitic in nature. They cover the bark of the trees and take food from them. Rafflesia Arnoldi of Sumatra is also a famous parasitic plant.