Pteridaceae is a family of ferns in the order Polypodiales, including some 1150 known species in ca 45 genera (depending on taxonomic opinions), divided over five subfamilies. The family includes four groups of genera that are sometimes recognized as separate families: the adiantoid, cheilanthoid, pteridoid, and hemionitidoid ferns. Relationships among these groups remain unclear, and although some recent genetic analyses of the Pteridales suggest that neither the family Pteridaceae nor the major groups within it are all monophyletic, as yet these analyses are insufficiently comprehensive and robust to provide good support for a revision of the order at the family level.
Description
Members of Pteridaceae have creeping or erect rhizomes. The leaves are almost always compound and have linear sori that are typically on the margins of the leaves and lack a true indusium, typically being protected by a false indusium formed from the reflexed margin of the leaf.
Taxonomy
Curtis's botanical magazine, Argyrochosma nivea var. tenera
As traditionally defined, the groups within Pteridaceae are as follows:
Adiantoid ferns (tribe Adianteae Gaudich. 1829); epipetric, terrestrial or epiphytic in moist habitats, rachis often dichotomously branching; sori relatively small and discrete with sporangia born on the false indusium rather than the leaf blade proper; only one genus:
Adiantum L. – maidenhair ferns
Cheilanthoid ferns; primarily epipetric in semiarid habitats; leaves mostly with well-developed scales or trichomes, often bipinnate or otherwise highly compound; sporangia mostly born in marginal sori with false indusia that are ± continuous around the leaf margins; several genera, including:
Argyrochosma (J.Sm.) Windham – false cloak ferns
Aspidotis (Nutt. ex Hook.) Copel. – lace ferns
Astrolepis D.M.Benham & Windham – cloak ferns
Cheilanthes Sw. – lip ferns
Myriopteris Fée – lace lip ferns
Notholaena R.Br. – cloak ferns
Pellaea Link – cliff brakes
Pteridoid...
