Three salt marsh fungi (Pleospora pelagica, P. vagans and Phaeosphaeria typharum) were examined for their ability to produce cell wall polysaccharidases when cultured in a medium containing cell walls isolated from Spartina alterniflora as the sole C source. Enzymatic activities detected in culture filtrates after 6 days of growth were .alpha.-L-arabinosidase, .alpha.-D-galactosidase, .beta.-D-glucosidase, .beta.-D-xylosidase, arabanase, cellulase, pectinase and xylanase. Not all fungi produced the same enzymes. Enzymatically active culture filtrates from these fungi, as well as from the salt marsh fungus Buergenerula spartinae, solubilized isolated cell walls as measured by reducing sugar liberation. The merits of using isolated cell walls as enzyme substrates are discussed.