Epiphyte
A plant that grows on another plant for support, without taking food from it.
Also: air plant
An epiphyte perches on a tree branch or trunk, where there is more light than on the forest floor. It is not a parasite. It takes water from rain and mist, and food from dust and fallen leaves. A large share of the world's orchids live this way, including the moth orchids and dendrobiums sold as pot plants and cut flowers. Many bromeliads and ferns are epiphytes too. This is why orchids are potted in bark chips and not in soil.