Final answer:
Mycorrhiza is a symbiotic association between fungi and plant roots, with two main types, ectomycorrhiza and endomycorrhiza (arbuscular mycorrhiza). Ectomycorrhizae form a mantle around the roots and are typical in forest trees, whereas endomycorrhizae have the fungal mycelium embedded within the root tissue, commonly found in most terrestrial plants.
Step-by-step explanation:
Mycorrhiza refers to a symbiotic association between a fungus and the roots of a plant. This relationship is crucial for plant nutrient uptake and overall health. There are two primary types of mycorrhizae: ectomycorrhizae and endomycorrhizae, also known as arbuscular mycorrhizae.
Ectomycorrhizae form a dense mantle around plant roots, with hyphae extending from the mantle into the soil to increase the surface area for absorbing water and minerals. It is commonly found in forest trees such as conifers, birches, and oaks. On the other hand, endomycorrhizae do not form a dense sheath; instead, their fungal mycelium penetrates the root tissue, establishing a direct exchange interface within the root cells themselves. Over 80 percent of terrestrial plants form endomycorrhizal associations with fungi belonging to the Glomeromycota.
Let's focus on ectomycorrhizae and their symbionts. The fungal symbionts in ectomycorrhizal associations can belong to various groups, including Ascomycota, Basidiomycota, or Zygomycota. These fungi envelop the roots with a sheath and hyphae that intermingle with root cells but do not invade them directly as in endomycorrhizae. Instead, a network known as a Hartig net surrounds the root cells, facilitating the exchange of nutrients and carbohydrates.