The Didymiaceae family, like all members of the Physarales order are distinguished by the presence of crystalline lime. Which is restricted to the peridium in the form of crystals or disks. Spores are typically dark brown to dark purple-brown

Sporangia stalked, sessile, or forming plasmodiocarps; sporangial wall normaly of two layers, containing deposits of lime in granules. Columella usually present, threads of the capillitium simple or branched, without lime.

Sporangia stalked, sessile, or forming plasmodiocarps; sporangia wall membranous or cartilaginous, with superficial crystals of lime either scattered over the surface or combined into a separable crust. Capillitium of branching threads, which are thickened at intervals with dark calyciform nodes, in normal developments without lime.