Fourstar is a genus of fungi in the family Mycetomiaceae. The genus contains four species, all of which are found in North America.
The first species to be described in the Fourstar genus was F. septentrionalis, which was discovered in Canada in 1892. The other three species, F. occidentalis, F. borealis, and F. australis, were all described in the United States between 1909 and 1912. All four species are found growing on dead wood or living trees; they are not known to cause any disease symptoms in their host plants.
The fruit bodies of Fourstar fungi resemble small cups or discs, ranging in color from pale white to dark brownish-black. They typically measure 1-3 cm (0.4-1 inch) across, and have a raised rim around the edge of the cup. The spores of these fungi are produced on the inner surface of the cup-shaped fruit body; they are released into the air when conditions are right for dispersal (usually during wet weather).
While not well studied, it is thought that Fourstar fungi play an important role in decomposing woody debris back into soil nutrients. These fungi help to recycle carbon and other essential elements needed by plants to grow and thrive.