Osmundaceae

Terrestrial ferns with non-scaly, short, hard, erect trunks or rhizomes. Stipes with 2 stipular expansions at the base. Fronds uniform or dimorphic, pinnately compound (mostly bipinnate) with circinnate vernation. Veins free. Sporangia non-soral, exindusiate, large, subglobular, maturing simultaneously; the annulus represented by a group of thick-walled cells near the distal end of each sporangium, dehiscing by a ventral-distal slit; the pedicel short and thick. Spores tetrahedral, green, without a perispore. 3 gen., trop. to temp.