Final answer:
A plant that takes nutrition from a living host is called a parasitic plant. It connects via a structure known as a haustorium to siphon nutrients and water.
Step-by-step explanation:
The term that describes a plant requiring nutrition from a living host plant is parasitic plant. These plants attach themselves to a host plant and obtain water and nutrients through a structure called a haustorium. This relationship is essential for the survival of the parasitic plant as it does not fully photosynthesize on its own and thus derives nutrients and water needed for growth from its host.