Final answer:
Roots that enable a plant to grow on another plant are known as epiphytic roots, which are a type of adventitious root.
Step-by-step explanation:
Roots that enable a plant to grow on another plant are called epiphytic roots. These roots are a type of adventitious roots that grow above ground. Epiphytic roots can be seen in plants like orchids, where they develop spongy tissue to absorb moisture, and in the banyan tree, which starts as an epiphyte and extends aerial roots to reach the ground for support. Contrary to a taproot system, which consists of a single main root like that of a carrot, or a fibrous root system, which is a dense network found in monocots like wheat, adventitious roots are specialized structures arising from non-root tissues.