The mycorrhizal relationship develops when certain fungi associate with plant roots. This relationship, known as mycorrhizae, is one of the important symbiotic associations in ecosystems. It plays a fundamental role in improving plants’ ability to obtain water and mineral nutrients from the soil. Fine fungal hyphae extend beyond the immediate root zone, enabling the fungi to explore a larger volume of soil and absorb nutrients, particularly phosphorus, which is essential for root growth and energy transfer within plant cells. In return, the plant supplies the fungus with sugars and carbon compounds produced through photosynthesis. The plant benefits from the fungus’s ability to access resources in soil regions that may be difficult for roots to reach on their own. This exchange highlights the importance of symbiotic relationships in improving the efficiency with which organisms obtain the resources necessary for growth and survival. There are several types of mycorrhizal fungi. Among the most prominent are arbuscular mycorrhizal fungi, which form branched structures inside root cortical cells, increasing the surface area available for exchange between the fungus and the plant. Another major group is ectomycorrhizal fungi, which surround the roots with a fungal sheath and extend their hyphae between certain root cells without usually penetrating the cells themselves. These groups differ in the plants with which they associate and in the nature of the interactions they establish. Connected fungal hyphae may form networks that extend through the soil and link the roots of multiple plants, potentially allowing certain resources and chemical signals to move through these networks. However, the extent and significance of such transfers depend on the fungal species, plant species, and environmental conditions. These networks should not be regarded as a conscious communication system among trees; rather, they represent complex biological and chemical interactions that remain the subject of scientific investigation. Mycorrhizal fungi contribute to improved nutrient uptake, plant growth, and the cycling of carbon and mineral nutrients. They also influence soil structure and stability through the spread of fungal hyphae and their interactions with soil components. Furthermore, some mycorrhizal associations may help plants tolerate drought and environmental stress by improving water and nutrient acquisition, although the extent of these benefits varies according to the plant species, fungal species, and surrounding conditions. Ecological and Agricultural Importance: Mycorrhizal fungi are essential components of sustainable ecosystems because of their role in plant nutrition, soil fertility, and biodiversity support. Their study is particularly important in sustainable agriculture, where certain species can be used to improve crop growth and nutrient-use efficiency while reducing reliance on agricultural inputs under suitable conditions. Therefore, understanding the relationship between plants and mycorrhizal fungi helps support the development of agricultural and environmental practices that maintain soil health and promote ecosystem stability. Al-Mustaqbal University – The First University in Iraq