Fomitopsis palustris is a species of polypore fungus in the family Fomitopsidaceae.

It causes brown rot, a disease of wood that results from the enzymatic breakdown of the wood component cellulose, but not lignin.

Several enzymes involved in the wood-decay process have been biochemically characterized.

[1] Fomitopsis palustris is known to possess three different cellulase enzymes.

[2] An endoglucanase, named EG-II, has been purified and characterized from this species in 2008; it is believed to assist in the wood rot process by loosening the polysaccharide network in cell walls by disentangling hemicelluloses associated with cellulose.