Mostly tropical and south temperate (except Woodwardia, which is north temperate).
Circumscription of genera is controversial, especially as to placement of those species now included in Blechnum. Characteristics holding the family together include the anastomoses of veins along the axes of the blade to form a series of areoles or a single continuous vein along which the sorus is borne, elongate sori with indusia opening toward midvein, bilateral spores, and chromosome base numbers of generally x = 28–36. Relationships of the family with both dryopteroid and athyrioid ferns have been suggested.
Stenochlaena tenuifolia (Desvaux) T. Moore, native to the Old World, was reported as escaped from cultivation in the 1930s in southern Florida; it has not been collected there recently. It is distinguished by having climbing stems and by having contracted, 2-pinnate fertile leaves with sporangia covering the abaxial surface.
Genera ca. 10, species ca. 250 (2 genera, 6 species in the flora).