Epiphytes growing on the branches of trees provide an example of the relationship known as?

Step 1: Analyze the question The question asks what type of relationship exists between epiphytes (plants growing on tree branches) and the trees that host them.

Step 2: Explain the concept Epiphytes are plants such as some orchids, ferns, and mosses that grow on other plants for physical support only. They make their own food by photosynthesis and absorb moisture from the air and rain. They do not take nutrients from the host tree.

This is a classic example of commensalism: a relationship in which one organism benefits (the epiphyte gets support and better access to light) while the other is neither helped nor harmed (the tree).

Step 3: Check each option

• A. Parasitism: The parasite takes food from the host and harms it. Epiphytes do not draw nutrients from the tree, so this is wrong. (Mistletoe is a different case: it is a partial parasite.)
• B. Commensalism: One partner benefits and the other is unaffected. This fits epiphytes on tree branches.
• C. Saprophytism: This means feeding on dead or decaying organic matter, like mushrooms and moulds. Epiphytes do not do this.
• D. Holophytism: This is the autotrophic mode of nutrition in which a plant makes its own food. It describes how the epiphyte feeds, not its relationship with the tree.

Step 4: Answer The correct option is B. commensalism.

Tip: Remember the pairs of symbols for symbiotic relationships:

• Commensalism: (+, 0), one benefits and the other is unaffected
• Mutualism: (+, +), both benefit
• Parasitism: (+, −), one benefits and the other is harmed

When you see "growing on" a plant for support only, think commensalism.