Alpine woodsia is a diminutive alpine fern that grows in rock outcrops, dry tundra and gravelly slopes in Denali, its leaves once pinnately divided. All fronds are fertile. Plants have green fronds, which grow up to 20 cm tall in clumps from a short rhizome. The leaflets are pinnately lobed, broadly triangular or diamond-shaped. The whole leaf is narrowly elliptic or obovate in shape. Sori are round, arranged on either side of the leaflet midvein. There are persistent stipes—but usually not dead leaves—in the clump above the rhizome. Stipes are hairy and few-scaled, with a joint at the base. The indusium is composed of long white hairs. There are two other Woodsia species in the park: Woodsia ilvensis, in which the stipe is scaly throughout (not just at the base), and Woodsia glabella, which lacks all hairs and scales above the joint at the base.
This species is perennial with deciduous leaves. Spores are produced mid-summer.
Like all ferns, this species is spore-producing. Spores germinate into tiny haploid gametophytes, which can be fertilized to become new, diploid ferns. This species is a hybrid, originating as a cross between Woodsia ilvensis and W. glabella (Windham 1993). It can form back-hybrids with W. ilvensis.
Alpine woodsia is a circumpolar species with a boreal-montane distribution. In North America, its range stretches east from Alaska to Maine and Greenland, and south to northern B.C. and it reaches into northern Minnesota and Michigan in the Great Lakes region. In Alaska, the species range is from the Brooks Range through the mountains and hills of central Alaska, to northern southcentral. Woodsia alpina is known from six sites in Denali, five from northern slopes of the Alaska Range, and one from Chitsia Mountain in the Kantishna Hills.
This is an uncommon high elevation species, the average elevation is 1196 m in Denali. It grows on moderately steep slopes, averaging 23 degrees incline. There are few more occurrences on southern aspects than northern.