The Dictionary Definition:"A type of mycorrhizae composed of a fungus sheath around the outside of root tips, with individual hyphae penetrating between the cortical cells of the root to absorb photosynthates."
In simple terms, this is the type of mycorrhizal fungus you can physically see with your own eyes and also the fruits (which most folks call mushrooms/truffles) that appear on or in the ground and quite often can be edible. Association of this fungus may be host specific to certain types of trees. For example the PT Mycorrhizae (The Dog Turd Fungus) often referenced here colonizes oaks, pines, firs, birch, willows, eucalyptus, cottonwoods, even Pecan trees. However it won't associate with such trees as maples, sycamores and such. These are trees with endomycorrhizal colonization which will be dealt with on a separate page.
These fungi associations are able to find and release nutrients in minerals that are unavailable to the plants on their own. Much like our own digestive system internally has beneficial bacteria for breaking down our food we eat into various sugars so that our bodies can absorb them and feed nutritionally. Without these associations we'd starve. Other creatures like Termites also have a Protozoa contained in their digestive tracts which digests the wood they chew up and swallow. Without these they'd starve on eating wood. These fungi also provide a source of antibiotics to the plants roots from potentially harmful pathogens to the roots. As mentioned before, researchers are also finding out that various plant species can be connected through this fungal network and actually exchange various photosynthates or carbons produced by these plants and may even exchange various chemical compounds to other completely different plants as a sort of chemical exchange agreement for which many plants derive health benefits from living in association with such neighbours. We call this community plantings and should be copied and replicated in any urban landscape, gardening or Habitat restoration project. All of this of course is fascilitated thru the grid network. The forest is actually far more sophisticated than most people realize. Most science based chemical systems created by big business actually destroys this system, hence the ill effects of various ecosystems around our globe. Trust me, not all scientists are on the same page despite what many defenders may think.
Next, let's illustrate just how these symbiotic relationships come about by means of a hardware viewpoint. We've already touched on many mycorrhizae are host specific. This means they will only form connections with certain plants, shrubs or trees. Like the Internet Networks around the globe with it's data bases, wiring & cabling connections, millions of computers with all their internal hardware and various software applications controlling all of this communications by sending and receive specific messages, the grid system between fungi and plants operate similarily. Plants manufacture specific acids which will attract a specific host which has the right fit. This can almost be compare to differing male and female adapters used by different countries around the globe for electrical connections. Here's a visual look at different fittings, but consider that out in the natural world the endless array of fittings and receptors are far more numerous and complex than the things achieved and created by humans.
|Mycorrhizae are often Host Species, needing|
just the right adapter for perfect fit
Fair Trade in the Underworld: the Ectomycorrhizal Symbiosis
"The ectomycorrhizal fungi have a beneficial impact on plant growth and nutrient cycling in forest ecosystems. The differentiation of an effective symbiosis induces a series of complex and overlapping morphogenetic processes in the colonizing mycorrhizal hyphae and lateral roots of host trees. Up- and down-regulation of gene expression is a major mechanism for controlling ectomycorrhizal symbiosis development and functioning. Transcript profiling studies led to the identification of genes that are required for fungal attachment, plant defense, and symbiosis-related metabolism. They showed that changes in morphology associated with mycorrhizal development were accompanied by alteration in transcript patterns. Comparison of the genomes of the different pathogenic and saprobic fungi with the ectomycorrhizal Laccaria bicolor genome revealed that the symbiont genome encodes several features found in saprotrophic and biotrophic fungi, but it lacks the extensive set of cell wall hydrolytic enzymes encoded by soil white-rot fungi and necrotrophic phytopathogens. Genome-wide studies are providing crucial insights into the genetic makeup of mycorrhizal interactions"
Some Common well known Ectomycorrhizae Fungus
Psiolithus tinctorius references:
|Leccinum aurantiacum references:|
Ectomycorrhizae - Thelephora terrestris
Some great references: