Dennstaedtiaceae is one of fifteen families in the order Polypodiales, the most derived families within monilophytes (ferns). It comprises 10 genera with ca 240 known species, including one of the world's most abundant ferns, Pteridium aquilinum (bracken). Members of the order generally have large, highly divided leaves and have either small, round intramarginal sori with cup-shaped indusia (e.g. Dennstaedtia) or linear marginal sori with a false indusium formed from the reflexed leaf margin (e.g. Pteridium). The morphological diversity among members of the order has confused past taxonomy, but recent molecular studies have supported the monophyly of the order and the family. The reclassification of Dennstaedtiaceae and the rest of the monilophytes was published in 2006, so most of the available literature is not updated. Characteristics Terrestrial or scrambling (scandent) over rocks or stones (epilithic) or occasionally over other vegetation (epiphytic) Rhizomes long-creeping, occasionally short-creeping Rhizomes bearing jointed hairs, or peltate, non-clathrate, entire scales, or both, with transitions Rhizomes often solenostelic or protostelic with internal phloem, or rarely short and dyctiostelic Petioles close or more often remote, non-articulate, usually with one or two, less often several vascular bundles Petioles often with epipetiolar buds Petioles usually with gutter-shaped vascular strand (open end adaxial) Petiole either pubescent or glabrous Mature leaves often glabrous at maturity, or bearing (mostly articulate) hairs, not scaly; hairs often persistent on leaf axes Blades often large Blades often 2-3 pinnate to decompound, can be 1-4 pinnate or more divided, mostly distinctly anadromous Veins free, or forked, or pinnate, ending with more or less thickened ends behind the margin, rarely vanishing, free included veinlets none Stomata anomocytic and/or polocytic Sori near the margin, or submarginal, sometimes fused with the blade to form a cup or pouch or obscured in a recurved portion of the blade margin joining 2 to very many vein ends Sori mostly linear, may be discrete Indusia linear or cup shaped at blade margin, or reflexed over sori Indusia sometimes wanting and replaced by the reflexed, more or less modified leaf margin; sometimes such a "false" indusium present beside a "true" one Sporangium stalk with 1-3 rows of cells Sterile appendages among sporangia none or if present not or little differentiated from epidermal appendages Capsule usually with well-differentiated stomium Spore tetrahedral and trilete, or reniform and monolete, variously sculptured Gametophyte known in comparatively few representatives Gametophyte green, hairless, cordate, and the plate stage is reached soon