Final answer:
An epiphyte is a plant that grows on another plant without harming it, utilizing their specialized roots for moisture and nutrients from the air or accumulated organic material rather than the host plant itself.
Step-by-step explanation:
A plant which grows on another plant without apparent harm to the host plant is called an epiphyte. Epiphytes do not rely on their host plant for nutrition but may use it for support. They have specialized roots, some of which are used for clinging onto the host plant, and others for absorbing moisture and nutrients from the atmosphere or accumulated humus.
This is in contrast to parasitic plants, which do depend on the host for survival and can potentially harm the host in the process of obtaining water and nutrients. Parasites may form structures like haustoria to penetrate their hosts and access their resources. However, epiphytes simply share a physical space without taking nutrients from or contributing to the host's welfare.