Polystichum imbricans (D. C. Eaton) D. H. Wagner

Imbricate sword fern, narrow-leaved sword fern

Etymology Imbricans means overlapping, like tiles or shingles.
Description Rhizome: erect.
Frond: 50 cm high by 11 cm wide, evergreen, monomorphic, blade/stipe ratio: 1:1 to 4:1.
Stipe: grooved, varies: 8 - 26 cm, long, lanceolate, reddish-brown scales, falling early, vascular bundles: 4 or more, in an arc.
Blade: 1-pinnate, linear, glossy, sometimes linear pale brown scales on the rachis.
Pinnae: 20 to 30 pair, held horizontally, with an upward ear at the base; margins entire, tipped with a short, sharp spine; veins free, forking.
Sori: round, except for the upward lobe, midway between margin and costa, in a very straight row, and each at the terminus of a veinlet, indusium: peltate, central, sporangia: yellowish.
Culture Habitat: shaded or exposed outcrops, banks, slopes, rocky areas. Distribution: West Coast of North America. Hardy to -20C, USDA Zone 6.
Synonyms
Aspidium munitum Kaulfuss var. imbricans D. C. Eaton
Polystichum munitum (Kaulfuss) C. Presl subsp. imbricans (D. C. Eaton) Munz
Polystichum munitum var. imbricans (D. C. Eaton) Maxon
Aspidium munitum var. nudatum D.C. Eaton
Polystichum imbricans
Polystichum imbricans. a) fronds, b) fertile pinna, sori confluent.  Illustration by V. Fulford from Ferns and Fern Allies of Canada, William J. Cody and Donald M. Britton, 1989, Agriculture Canada, used with permission.
Notes
ssp. curtum the pinnae are in the plane of the blade, not held horizontally, and the sori are close to the margin rather than the midrib. The herbarium image points to this taxon, but is not so designated.
Compare to P. munitum which is similar but a much larger plant. P. munitum also has a scaly rachis with reddish-brown scales whereas this plant has sparse, pale brown scales above the stipe.
Nomenclature imbricans means overlapping. D.C. Eaton was misled by herbarium plates, which converts closely-spaced pinnae into overlapping pinnae from their horizontal position in real life. Many descriptions mention overlapping erroneously, but this one inscribes it.
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