Like a black light poster come to life, a group of bioluminescent fungi collected from Ribeira Valley Tourist State Park near São Paulo, Brazil, emanates a soft green glow when the lights go out. The mushrooms are part of the genus Mycena, a group that includes about 500 species worldwide. Of these only 33 are known to be bioluminescent—capable of producing light through a chemical reaction. Since 2002 Cassius Stevani, professor of chemistry at the University of São Paulo; Dennis Desjardin, professor of mycology at San Francisco State University in California; and Marina Capelari of Brazil's Institute of Botany have discovered ten more bioluminescent fungi species—four of which are new to science—in Brazil's tropical forests. The work, Stevani says, has increased the number of glowers known since the 1970s by 30 percent.