Thumbnail Photographs of Ectomycorrhiza Types

Mycorrhizae are long-lived symbioses between fungi andthe roots of higher plants. The fungi extend the nutrient-absorbing surfacearea of the roots; produce extracellular enzymes which increase phosphorousand nitrogen availability; increase host drought tolerance; and protectagainst pathogens. In return, the fungi receive host photosynthate as theirmain source of carbon. Ectomycorrhizal fungi (EMF) are essential for hostplant nutrient uptake and play important roles in nutrient cycling in manyforests. For example, an estimated 50 to 70 percent of the net annual productivitymay be translocated to roots and associated mycorrhizal fungi.

Exudates and hyphae of EMF form a major link between above-ground producersand soil food webs, providing carbon for a wide range of bacteria, protozoa,arthropods and microfungi. Mycorrhizal fungi are also important in above­groundfood webs. EMF, with few exceptions, produce macroscopic sporocarps (mushroomsand truffles) that are important in the diets of animals, especially smallmammals. Some rodents such as the California red-backed vole (Clethrionomyscalifornicus) and northern flying squirrels (Glaucomys sabrinus)rely on these sporocarps for over 90% of their food supply and are primaryprey for species such as the Northern Spotted Owl.

These ectomycorrhizae are from soil cores taken at theSiskiyou Intergrated Research Site in southwest Oregon. Photos by D.L.Luoma.

Click on thumbnail to load enLARGEment. Last modified March 7, 1997.

C6 unknown fungus

D6 Truncocolumella citrina on Pseudotsuga menziesii

E2 Lactarius rubrilacteus on Pseudotsuga menziesii

F8 Leucogaster rubescens on Pseudotsuga menziesii

I6 Hysterangium sp. on Lithocarpus densiflorus

Mycology Team Homepage

Address Questions to:
Michael Castellano