What is host and parasitic plant

The host is an animal or a plant that harbors another organism inside or near their body in a symbiotic relationship.

In other words,

An animal or plant that nourishes and supports a parasite and the host does not get the benefit in fact often gets harmed by the association.

For example, viruses, fungus, and tapeworms are parasites in the intestines of humans. In this scenario, humans are the 'host'.

A parasitic plant is a heterotrophic plant that derives some or all of its nutritional requirements from another living plant because they lack chlorophyll and hence cannot make its own food.

For example- Cuscuta (Amarbel) is a yellow tubular plant climb on other trees known as a host plant and absorb the readymade food.