All fungi reproduce by spores . Especially important in recycling the carbon locked up in cellulose and lignin. Economically the most important of these are crop pathogens. A. Fungus infects grains , whose insides become filled with smelly black spores . A superior ability to absorb relatively insoluble phosphate compounds from the soil.
Many modern plants are unable to compete in nature without their mycorrhizal partner.
For them the relationship is obligate . A. Pine trees are an example.