Answer: Commensalism (Symbiotic relationship)
Explanation:
Commensalism is a type of symbiotic relationship in which one species gets benefits while the other species remain unaffected.
Orchids are epiphytes which grows on the inner branches of trees of rainforest that helps in taking nutrients directly from the air around them and sometimes from the decaying organic matter of their host tree. Epiphytic orchids stores water in their stems and compensate in dry periods. Trees having rough barks that holds humus and water in it's crack supports orchids better than other trees with smooth barks.
