Sword Fern (Polystichum munitum). 1. Portion of frond. 2. Pinna (underside) illustrating position and character of sori. 3. Portion of stalk illustrating its scaly character.

SWORD FERN.
(Polystichum munitum (Kaulf.) Presl)

Probably the best known fern in the deep woods of the Canadian and Humid Transition zones as it is large, distinctive in appearance and evergreen. Prefers a habitat of moist humus but may often be found in poorer soils. The botanical range includes the area from Alaska to Idaho and Montana and south along the Pacific Coast to California. Locally it is found from the lowest elevations along the park boundaries to nearly 5000 feet. Fronds are tufted, of tough leathery texture, one compound, up to four feet in length and lanceolate in outline; widest very near the basal pinnae-2-10 inches at widest point. Pinnae lanceolate, edged with recurved doubly serrate teeth each tipped with a strong prickle and having a conspicuous ear-like projection on the upper side of the pinnae at the base. Pinnae are attached to the stem by a short petiole. Leaf stalks 2-20 inches long, being about 1/4 as long as the entire blade; very scaly with chaffy brown scales which are also present on the mid-vein of the pinnae upon their under side. Spores borne in large conspicuous round sori, in two or more rows and about midway between margin of the pinnae and mid-vein. Indusium present, round and conspicuous before full maturity of the spores. Rhizome stout, woody and either erect or decumbent; scaly.

The common name refers to the stout, lanceolate shape of the fronds with their sharply serrate teeth on the pinnae. It is sometimes called Christmas Fern because of its confusion with eastern species in the same genus.

SYNONYMS: P. munitum, var. imbricans Max.; Aspidium munitum Kaulf.

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