Two-celled ascospores of Hypomyces lactifluorum

The ascospores are discharged from the fruitbodies (perithecia) embedded in the infected mushroom.  Spores are dispersed by wind to fresh sites where  they have the opportunity (or not) to attack species of Russula or Lactarius.  Ascospores are very distinctive and are fusiform (= tapered to a point at both ends), septate (=with cross wall), and have a finely roughened outside wall.