Endomycorrhizae—also referred to as Vesicular Arbuscular Mycorrhizae (VAM)—symbiotically associate with about 90% of the plant kingdom. Their origins date back 350–460 million years and were important in the colonization of land by vascular plants. Endomycorrhizae form an intercellular attachment by penetrating the cell wall of plant roots and forming branched structures called arbuscules within the root cells. These arbuscules provide an extensive surface area for the exchange of nutrients through the cell membrane. Mycelia from endomycorrhizae extend from the plant roots into the surrounding soil, gathering nutrients and water bringing them back to the plant's roots.

Ectomycorrhizae symbiotically associate with about 5% of the plant Kingdom, mostly conifers and a few deciduous hardwood trees. They form an extracellular attachment by creating a fungal sheath around the root tips of the tree. The fungus excretes organic chemicals that cause the root cells to become more permeable allowing for greater exchange of gas, water and nutrients. The mycelium of the fungi forages into the soil great distances and transports the nutrients and water back to the root tips of the tree.

Alder
Aspen
Cottonwood
Eucalyptus
Poplar
Willow