This is an evolutionarily ancient and very diverse group of plants that are often placed together in the taxonomic Division Pteridophyta, which is comprised of vascular plants that do not produce seeds, but instead reproduce and are dispersed through spores. Pteridophytes have free-living, independent gametophytes and produce motile sperm. The morphological and evolutionary diversity contained within this division of the plant kingdom is considerable. In Denali the "lower plants" are represented by the following groups: true ferns (Blechnaceae, Dryopteridaceae, Pteridaceae, Thelypteridaceae, and Polypodiaceae) the horsetails (Equisetaceae), Club mosses, (Lycopodiaceae), Spike mosses (Selaginellaceae) and quillworts (Isoetaceae).
The most species-rich fern family in the Denali flora is the Wood fern family (Dryopteridaceae; 13 species), followed by the Maidenhair fern family (Pteridaceae; 3 species). There is one species each from the three other fern families that occur here: Chain fern family (Blechnaceae), Polypody family (Polypodiaceae), and Maiden fern family (Thelypteridaceae). Closely related to the true ferns are an ancient and peculiar-looking group of spore-bearing plants appropriately called the Moonworts, which are placed by taxonomists in the Adder-tongue plant family (Ophioglossaceae). There are seven species of moonworts known to occur in the flora of Denali National Park. Except for the most common member of this genus in the park, which is Botrychium lunaria, these species have very interrupted and spotty distribution patterns – they are found only rarely, even by the keenest observers. Moonworts are most commonly found in lush and moist, (but not wet) meadow habitats in subalpine slopes and river terraces in association with dense growths of grasses such as Festuca altaica, Poa spp and forbs, including wild geranium (Geranium erianthum), Monkshood (Aconitum delphinofolium) and Veronica (Veronica wormskjoldii).