Step 1: Mycorrhiza (misspelled as Mycohhroeza in the question) is a symbiotic association between a fungus and the roots of higher plants. Step 2: The fungus helps the plant in the absorption of essential nutrients (like phosphorus) from the soil, while the plant provides the fungus with energy-yielding carbohydrates. Step 3: Since both organisms benefit from this interaction (+/+), it is a classic example of mutualism.