Sp. Pl. 2: 1063. 1753; Gen. Pl. ed. 5, 484, 1754.
Plants terrestrial. Stems creeping; tips often somewhat erect. Leaves dimorphic; fertile leaves erect, often notably smaller than sterile leaves in length and width. Blades 1–2-pinnate; pinnae monomorphic to dimorphic, pinnatifid or pinnate.
Nearly worldwide, tropical and temperate regions.
Species 10 (3 in the flora).
|1||Fertile leaves with pinnae monomorphic, all spore-bearing; tuft of hairs persistent on abaxial surface of pinnae near base.||Osmunda cinnamomea|
|1||Fertile leaves with pinnae dimorphic, some spore-bearing, some not; tuft of hairs absent on abaxial surface of pinnae near base.||> 2|
|2||Sterile leaves 2-pinnate with pinnules sessile.||Osmunda ruggii|
|2||Sterile leaves pinnate-pinnatifid or 2-pinnate with pinnules stalked.||> 3|
|3||Fertile pinnae apical, sterile leaves 2-pinnate.||Osmunda regalis var. spectabilis|
|3||Fertile pinnae medial, sterile leaves pinnate-pinnatifid.||Osmunda claytoniana|