17. Dryopteris filix-mas (L.) Schott (Gen. Fil., plate 9. 1834).—Common male-fern.—Fig. 18.  

Lastrea filix-mas (L.) C. Presl

Rhizomes erect, stout, producing offshoots. Frond 35—150 cm long, 5—30 cm wide; stipe 1/4—1/2 the length of the blade, sparsely to moderately scaly, the scales mixed, larger ones mostly narrow ovate to broad ovate, to ca. 14 mm long, 6 mm wide, margins erose, sparsely and irregularly fimbriate and toothed, membranous, pale brown, rachis scales same as the stipe scales except smaller, narrower and more triangular; blades pinnate-pinnatifid to 2-pinnate at the base next to the rachis, oblong to obovate-lanceolate, usually narrowed to a truncate base, more or less herbaceous, green, slightly paler beneath; pinnae, short stalked; pinnules (or segments) oblong to slightly tapered, the margins crenate-serrate to serrate, the serrations sometimes toothed, the segment apex rounded with more or less acute, sharp teeth. Sori large, 4—6 per segment; indusia when young to mature, white, round, thin, spreading.

Dryopteris filix-mas is a sexual tetraploid, species native to Europe, western Asia, the far-western Himalayas, and North America, where it forms large clumps in lowland or alpine forests or in open places on rocks. The species has escaped and become naturalized in New Zealand.

Dryopteris filix-mas originated from a cross between D. oreades and D. caucasica and is intermediate in its morphology between these two species (Fraser-Jenkins 1976, 1989; Fraser-Jenkins and Corley 1972). It has long been confused with D. oreades and D. affinis and its subspecies, which have been called the "D. filix-mas group" as a group of three species, with D. caucasica subsequently being added. The complex was sorted out first by Wollaston (1915) and finally by Manton (1950). Dryopteris filix-mas lacks the dark blotch on the costa where it joins to the rachis (Jermy and Camus 1991), although rarely some plants have faint dark streaks or spots, especially on old leathery fronds exposed to the sun. The segments which are usually slightly tapered and toothed along the sides, the wider, pale membranous stipe scales, the more deciduous habit, the mid-green matte fronds and the less inflexed indusium help to distinguish D. filix-mas from D. affinis which has parallel-sided, more truncate segments usually with entire side margins, narrow golden-brown stipe scales, glossy dark green fronds, and a less deciduous habit. Dryopteris filix-mas hybridizes with D. affinis. A commonly sold hybrid is D. x complexa Fraser-Jenkins which is discussed here under D. affinis.

This species is part of European folklore. The rhizomes were formed into amulets, called St. John’s hand, and worn as protection from evil spirits. Also, the rhizomes of D. filix-mas have been used as a valid medication for intestinal worms.

Dryopteris filix-mas has spreading to arching fronds which grow up to 100 cm long. It is hardy to a January average of 20°F, and is easy to culture in shade. It is deciduous, with fronds become prone in autumn then wither during the winter. It is tolerant of somewhat drier sites than other Dryopteris species.

Many cultivars are known but have been greatly confused as to their names. It is probable that many of the named cultivars actually belong to D. affinis. Present-day plants may not correspond to the description found in earlier literature due to confused labeling in gardens. A number of cultivar names not listed here circulate in the U.S. trade. The more common ones in the U.S. trade are:

Dryopteris filix-mas ‘Barnesii’.—Barnes’ male-fern.—Growth upright, narrow fronds, ca. 130 cm long, 10 cm wide, the pinnae short, wide, the pinnules narrowed at the base, oval, deeply lobed, the lobes often serrate or toothed, frequently double toothed. Matches earlier material by same name (Druery 1910).

Dryopteris filix-mas ‘Crispa Cristata’.—Like ‘Cristata’ of current trade, except the pinnules or segments crisped.

Dryopteris filix-mas ‘Cristata’.—Crested male-fern.—A group of cultivars with apices of he blade and pinnae ending in a small to medium sized tassel without long finger-like divisions. The current trade plant sold as ‘Cristata’ has a narrow elliptic blade and compact medium size tassels, sometimes the tassel at the blade apex quite large

Dryopteris filix-mas ‘Cristata Martindale’. —Wide elliptic blade, blade and pinnae with small crest, pinnae strongly falcate.

Dryopteris filix-mas ‘Decomposita’.—Large, broad, foliaceous frond, almost 2-pinnate, 60—80 cm long, fine textured, the pinnules failing to develop properly at the sides so thickened and incised with irregular teeth.

Dryopteris filix-mas ‘Grandiceps’.—Large crested male-fern.—Fronds slightly arching, rachis branching some distance from the fronds apex to form very large crests, pinnae narrow and trimly crested, vigorous grower.

Dryopteris filix-mas ‘Linearis’.—Pinnules or segments very narrow to nearly filiform. Originated from spore of ‘Decomposita’.

Dryopteris filix-mas ‘Linearis Congesta’.—A small plant with modestly narrowed pinnules or segments, the pinnae short and close together.

Dryopteris filix-mas ‘Linearis Cristata’.—Like ‘Cristata’ of current trade but the pinnules or segments greatly narrowed.

Dryopteris filix-mas ‘Linearis Polydactyla’.—Slender crested male-fern.—Blade broadly elliptic, divisions of the tassels on the blade and pinnae long and finger-like, the segments of the pinnae linear to nearly filiform or depauperate. Like ‘Linearis’ but with forked pinna apex.

Dryopteris filix-mas ‘Polydactyla’.—With tassels on the tips of the pinnae and blade, the divisions of the tassel long and finger-like.

Dryopteris filix-mas ‘Ramo-cristata’.—Like 'Cristata' of current trade but stipe branched.

Dryopteris filix-mas ‘Undulata Robusta’.—See D. X complexa under D. affinis.