mushroom, Agaricus bisporus ; hence the word "mushroom" is most often applied to those fungi ( Basidiomycota , Agaricomycetes ) that have a stem ( stipe ), a cap ( pileus ), and gills (lamellae, sing. lamella ) or pores on the underside of the cap. source: http://en.wikipedia.org/wiki/Mushroom Saprotrophic nutrition (pronounced