Vesicular Arbuscular Mycorrhizae (more commonly refered to as VAM) - Endomycorrhizae
In a Nutshell
Both animated images at the top are illustrating the contrasting differences between Ecto & Endo Mycorrhizae. Remember the Ecto forms around the various cell walls like mortar around bricks and it's also easily seen with the naked eye, it also forms what we call fruiting bodies or dumping the science speak more commonly known as Mushrooms or Truffles. The Endomycorrhizae actually penetrates and infects the inside of the cell walls and becomes part of the cells, they don't form fruiting bodies like mushrooms or truffles, but rather what are called Propagules which will be found under the ground among the roots. Theie hyphal strands are also more difficult to see without some magnifcation, but sometimes easily recognized if someone knows what to look for.
Take a look at the actual pictures (both illustrated a real life) of the internal workings the fungal connections provide within the cell walls.
The most widespread of mycorrhizae are the arbuscular mycorrhizas (VAM), sometimes called vesicular-arbuscular mycorrhizas. These are found world-wide on many crop plants, wild herbaceous plants and trees, as well as on pteridophytes and some bryophytes. The fungi that form these mycorrhizas are members of the zygomycota, such as Glomus and Acaulospora spp.
The last photo above is taken from Mycorrhizal Applications Inc of Oregon where Tomato plants are hydroponically grown and the display here is of the mycorrhizal VAM colonizing the roots. However PHC also used this method in growing and harvesting VAM Propagules.
Arbutoid mycorrhizas are of the ect-endo type and, among the Ericaceae, are found in the genera Arbutus, Arctostaphylos and Arctous. They are also found in Pyrola of the Pyrolaceae which is also in the Ericales [N.B. Some authors recognise this as a separate type of mycorrhiza]. There is a well-developed fungal sheath and a Hartig net restricted to the outer layers of cells. Extensive penetration of the outer cortical cells occurs and hyphal coils fill the cells. This type of mycorrhiza resembles the ectomycorrhizas formed with forest trees but differs from them because of the cell penetration. The fungi involved are Basidiomycetes and mainly species that form ectomycorrhizas with forest trees.
The presence of the fungal sheath, as in ectomycorrhizas, insulates the host from the soil. Hence all minerals absorbed by mycorrhizal roots must pass through this sheath.
Thanks to L.E. Chinnery
More will be added as time goes on.