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


POLYSTICHUM
Sword Fern

Few to many fronds arise on the end of a stout rootstock. Evergreen fronds have a leathery texture, leaf bases are covered with papery brown scales. A large lobe occurs on upper side at base of each pinna. Sori are round with a peltate indusium, i.e., like an umbrella, but smooth around the margins.

SWORD FERN

Polystichum munitum (Kaulf.) Presl. (Fig. 40, 41)

Dark green shiny fronds 1 to 2 feet or occasionally as much as 3 feet long, lanceolate in outline, and pinnate. Round indusium slightly depressed in the center where stalk of the indusium is attached. Mature sporangia normally protrude beyond the edge of the indusium. Sori arranged in 2 rows down each pinna, the margins of pinnae being serrately toothed, the apex acute.

The Sword Fern and its variations are easily transplanted into gardens if kept in cool or at least partially shaded areas. It makes an excellent addition to bouquets because its shiny dark green fronds last well if kept in water and the pinnace do not drop off.

This species occurs in the Sierra Nevada up to 7,000 feet in elevation in open and wooded places where there is sufficient moisture. It is common in the Coast Range in the Redwood belt and is found as far north as Washington and Alaska, and in western Montana.

Fig. 40 SWORD FERN (Polystichum munitum). IMBRICATED SWORD FERN (form imbricans). NUDE SWORD FERN (form nudatum)
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Fig. 40 SWORD FERN (Polystichum munitum). Upper: Many dark green shiny fronds arise from a short rhizome. Grows in open places on mountain sides. Lower L. to R: Pinnae of SWORD FERN, IMBRICATED SWORD FERN (form imbricans). and NUDE SWORD FERN (form nudatum), showing circular indusium common to all varieties.

Fig. 41 Right: SWORD FERN (Polystichum munitum). NUDE SWORD FERN (form nudatum)
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Fig. 41 Right: SWORD FERN (Polystichum munitum). On a fertile frond, sori commonly found on all pinnae. Left: NUDE SWORD FERN (form nudatum). Sori commonly found on upper half of a fertile frond.

NUDE SWORD FERN

Polystichum munitum Presl. form nudatum (D. C. Eat.) Broun (Fig. 40, 41)

P. munitum var. nudatum

Fronds 6 to 10 inches long, stalks with scales only at base. Pinnae scattered, only slightly lobed on upper side at base. Sori confined to upper half of the frond.

Found occasionally in the Sierra Nevada from Mariposa to Nevada Counties. May be observed on the 4-mile Trail to Glacier Point, and along Ledge Trail.

IMBRICATED SWORD FERN

Polystichum munitum Presl. form imbricans (D. C. Eat.) Clute (Fig. 40, 42)

P. munitum var. imbricans

A small fern, usually not more than 15 inches high, stalk very chaffy at base. The distinctive features of this variety are the crowded pinnae which are imbricated or overlapping Pinnae are obliquely inclined upward. Sori occur only on the upper half of the fronds.

Known in the Sierra from Plumas County and Yosemite where it may be observed on any trails up the southern walls of Yosemite Valley, it always appears in drier places and may be an ecological variation. It is distributed from California to British Columbia.

Fig. 42 IMBRICATED SWORD FERN (Polystichum munitum form imbricans)
[click to enlarge]

Fig. 42 IMBRICATED SWORD FERN (Polystichum munitum form imbricans). One frond showing the closely crowded pinnae which overlap, and the scales at the base of the frond.



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