A)
Sporangia exposed in simple or branched clusters, the clusters lacking firm or thickened tissue and not persisting over winter; annulus of
sporangium poorly differentiated or none.
B)
Sporangia concealed in modified divisions of the blade of the fertile fronds, these divisions becoming firm and capsule-like; fertile fronds
persisting over winter; annulus sharply differentiated, forming a ring around the sporangium.
