Mycorrhizae and Mycelium Your Best Allies in the Garden
Mycorrhizae, a mutual partnership between certain soil fungi and fine root tips, contribute to plant growth and vigor by increasing both water and nutrient uptake, especially nitrogen (N) and phosphorus (P). Because they are smaller and more numerous, the fungal hyphae (thread-like filaments that form the basic cellular unit of filamentous fungal structures) increase root surface contact with the soil, while the fungi are supplied with a reliable source of carbon. Two types of mycorrhizae are found on most trees-ectomycorrhizae (EM) and endomycorrhizae-also called vesicular-arbuscular mycorrhizae (VAM). VAM is the type usually sold as a soil supplement. The EM fungi are mainly mushroom-forming basidiomycetes, while the VAM fungi are Zygomycetes, most of which form microscopic underground spores. The majority of plants, including many trees, are colonized by VAM fungi, while EM are almost exclusively limited to woody species, mushrooms like hanging out with trees. Some plants can have both VAM and EM fungi.
Mycelium (pl.: mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Its normal form is that of branched, slender, entangled, anastomosing, hyaline threads. Fungal colonies composed of mycelium are found in and on soil and many other substrates. A typical single spore germinates into a monokaryotic mycelium, which cannot reproduce sexually; when two compatible monokaryotic mycelia join and form a dikaryotic mycelium, that mycelium may form fruiting bodies such as mushrooms. A mycelium may be minute, forming a colony that is too small to see, or may grow to span thousands of acres as in Armillaria.
Have you ever wondered what is the world’s largest organism? When thinking of the largest organism on earth, you tend to think of massive blue whales or giant redwood trees. Although those are both great guesses, they are in fact not the largest organism. In fact, they are not even close. Surprisingly, this title is held by a fungus known as Armillaria solidipes (Honey fungus). Scientists find a network of this fungus in the pacific northwest which spans 5.5 kilometres across. This is equal to roughly 2,384 acres, and they estimate it to be over 2000 years old.
This fungus consists of visible above ground mushrooms and a large underground network of mycelia. The fungus gets so large through genetic clones joining together and creating this extensive mass.
Through the mycelium, a fungus absorbs nutrients from its environment. It does this in a two-stage process. First, the hyphae secrete enzymes onto or into the food source, which break down biological polymers into smaller units such as monomers. These monomers are then absorbed into the mycelium by facilitated diffusion and active transport.
Mycelia are vital in terrestrial and aquatic ecosystems for their role in the decomposition of plant material. They contribute to the organic fraction of soil, and their growth releases carbon dioxide back into the atmosphere (see carbon cycle). Ectomycorrhizal extramatrical mycelium, as well as the mycelium of arbuscular mycorrhizal fungi, increase the efficiency of water and nutrient absorption of most plants and confers resistance to some plant pathogens. Mycelium is an important food source for many soil invertebrates. They are vital to agriculture and are important to almost all species of plants, many species co-evolving with the fungi. Mycelium is a primary factor in some plants' health, nutrient intake and growth, with mycelium being a major factor to plant fitness.
