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Ferns of the Sierra (1960) by Robert J. Rodin


ATHYRIUM

Medium to large ferns, rhizome usually unbranched, sometimes tufted. Fronds large, spreading, bi- to tri-pinnate and erect. Sori on underside of pinnae in rows, oblong or moon-shaped, angled oblique to the midrib. Indusium shaped like sorus or absent. Located in moist places, often shady or protected places in forests, sometimes by streams or meadows.

KEY TO THE SPECIES:

Leaf segments crowded on fronds, indusium oblong to moon-shaped, fringed with cilia A. filix-femina
Leaf segments narrow, oblique, indusium absent A. alpestre

LADY FERN

Athyrium filix-femina (L.) Roth
(Fig. 13)

A. filix-femina var. californicum

Fronds 2 to 4 feet high, quite broad, often tapering toward the base, arising from a short rhizome. Leaf forms variable from deeply incised with toothed lobes, to completely separate pinnules. Dorsal sort are oblong to moon-shaped, usually toothed or with hair-like cilia on margins of the indusium.

Grows in shady or protected moist places, often in forests, from 4,000 to 8,000 feet elevation in the Sierra and is known from Idaho to Mexico, and in Europe and Asia. This fern does well in gardens in cooler climates, especially if given sufficient moisture. It does not tolerate wind.

ALPINE LADY FERN

Athyrium alpestre var. americanum Butters (Fig. 14)

Athyrium americanum
Phegopteris alpestris var. americanum
Phegopteris alpestris

Plants 1/2 to 2 1/2 feet high, usually rather large, fronds nearly tripinnate. Sori round, very small, on veins below the apex of pinnae. Indusium absent. Fronds narrower than preceding species, although frequently resembling them in appearance.

This fern is found in moist meadows, in ravines and along creeks at higher elevations in the Sierra Nevada from 7,000 to 11,000 feet. It is distributed from California into northwestern Canada and Alaska and it is known from Colorado. It is also known from Lassen Volcanic National Park, and may be seen in Yosemite on Mt. Hoffman, in Iceberg Pass, and along Unicorn Creek.

Fig. 13 LADY FERN (Athyrium filix-femina)
[click to enlarge]

Fig. 13 LADY FERN (Athyrium filix-femina). Upper: Habitat in moist soil near a stream in a wooded area. Lower right: Young stage of sori when flap-like indusium covers sorus. Lower left: Older stage when enlarging sporangia in the sorus push back and cover indusium or cause it to fall off.

Fig. 14 ALPINE LADY FERN (Athyrium alpestre var. americanum)
[click to enlarge]

Fig. 14 ALPINE LADY FERN (Athyrium alpestre var. americanum). Left: A small frond. Right: One branch from a large frond. This species has no indusium.



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