4. Polystichum braunii (Spenner) Fée, 5: 278. 1852.
Braun's holly fern, polystic de braun
Aspidium braunii Spenner, Fl. Friburg. 1: 9, plate 2. 1825; Polystichum braunii subsp. purshii (Fernald) Calder & Roy L. Taylor; P. braunii var. purshii Fernald
Stems erect. Leaves monomorphic, arching, 2--10 dm; bulblets absent. Petiole 1/8--1/6 length of leaf, densely scaly; scales light brown, gradually diminishing in size distally. Blade broadly lanceolate, 2-pinnate; base narrowed. Pinnae oblong-lanceolate or falcate, proximal pinnae ± rectangular, not overlapping, in 1 plane, 2--10 cm; base oblique except proximal 3--4 pinnae, where auricles not developed; apex acute, subapical and apical teeth same size; microscales filiform to linear, lacking projections, dense abaxially, sparse adaxially. Pinnules ± stalked, short-falcate to oblique-rhombic, acroscopic auricle well developed on proximal pinnules; margins dentate, with slender bristle tips; apex broadly acute. Indusia ciliate. Spores brown. 2 n = 164.
Moist places in boreal forests; interior moist forests; 0--300 m; St. Pierre and Miquelon; B.C., N.B., Nfld., N.S., Ont., Que., Yukon; Alaska, Conn., Idaho, Maine, Mass., Mich., Minn., N.H., N.Y., Vt., Wis.; Eurasia.
Because no diploid ancestors have been found, Polystichum braunii is thought to be an ancient tetraploid. Its sterile hybrid with P . acrostichoides , P . × potteri , is discussed under P . acrostichoides . Polystichum braunii × lonchitis has been reported from southeast Alaska (S. L. Welsh 1974). This hybrid has been cytologically confirmed in Europe and named P . × meyeri Sleep & Reichstein (A. Sleep and T. Reichstein 1967). It has narrower and less divided leaves than P . braunii and poorly developed auricles. Polystichum braunii × lonchitis was described by J. Ewan (1944), but the type (from British Columbia) is P . braunii × munitum (A. Sleep and T. Reichstein 1967). This latter hybrid is the postulated progenitor of P . setigerum (D. H. Wagner 1979). North American P . braunii has been segregated as var. purshii Fernald, distinguished from European populations (var. braunii ) by having broader microscales.