(alpine woodsia)
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Photo of Woodsia alpina by Mary Beth Cook
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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.
Details are shown in the Plots & Charts found at right, depicting recent Denali data.
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.
Details are shown in the Plots & Charts found at right. For more on how to interpret these figures, visit Understanding Data Presented.
These plants grow on 'calcareous rocks in mountains' (
Hulten 1968).
Dry slopes and rocky sites.
