Curvularia protuberata is a species of fungus

Fungus

A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

 in the Pleosporaceae

Pleosporaceae

Pleosporaceae is a family of sac fungi. The taxonomic relationship of this family to associated genera is still not determined.-Genera list:* Cochliobolus Drechsler* Crivellia Shoemaker & Inderbitzin...

 family. It forms a mutualistic relationship with Dichanthelium lanuginosum

Dichanthelium lanuginosum

Dichanthelium lanuginosum is a species of grass. It grows in geothermal areas of Yellowstone National Park, USA. It is able to withstand high temperatures and high acidity in its rhizosphere. In 2007 it was found that the heat tolerance is conferred to the grass by a symbiosis between a fungus and...

(panic grass) and Curvularia thermal tolerance virus

Virus

A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

 that allows the grass to grow in soils that are far warmer than it normally tolerates. The mutualism allows the grass to thrive in soil that is 65°C in Yellowstone National Park

Yellowstone National Park

Yellowstone National Park, established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872, is a national park located primarily in the U.S. state of Wyoming, although it also extends into Montana and Idaho...

. Experiments have shown that the plant can only survive when it is infected by C. protuberata and when C. protuberata is also infected with the virus. This is an example of a tritrophic interaction, as three organisms are interacting.