欧洲羽节蕨 ou zhou yu jie jue

Polypodium dryopteris Linnaeus, Sp. Pl. 2: 1093. 1753; Aspidium dryopteris (Linnaeus) Baumgarten; Carpogymnia dryopteris (Linnaeus) Á. Löve & D. Löve; Dryopteris linnaeana C. Christensen; Lastrea dryopteris (Linnaeus) Bory.

Rhizomes slender, creeping, black, shiny, apex clothed with brown ovate-lanceolate scales. Fronds distant; fertile lamina (15-)20-30(-50) cm; stipe stramineous, 10-22(-35) cm, slender, with sparse scales at base; lamina nearly tripartite, usually 2-pinnate-pinnatifid, pentagonal-ovate or broadly ovate-triangular, 7-15(-20) cm long and wide, thinly herbaceous or submembranous, base broadly cuneate, apex acuminate; basal pair of pinnae nearly as large as other portion of lamina, narrowly triangular, (3.5-)5-9(-12) × 2.5-4(-7) cm, pinnate-pinnatifid, base subtruncate, with stalk (0.8-)1-1.5(-2.5) cm, portion of rachis between basal pinnae and central lamina ca. 3 cm; pinnules 5 or 6 pairs, oblong-lanceolate, 1.5-2(-4) × 0.5-2 cm, base rounded-cuneate, sessile, apex acute or acuminate, opposite or subopposite, spreading; largest pinnules with 6-10 pairs of segments, segments approximate, oblong to narrowly ovate, ca. 4 mm, lobed to narrow costular wing, entire to shallowly lobed at margin, rounded-obtuse at apex; second basal pair of pinnae 1.5-4 cm apart from basal pair, sometimes shortly stalked, upper pinnae sessile; veins pinnate in segment, simple, oblique, visible abaxially; rachis and costae slender, eglandular. Sori small, exindusiate, orbicular, abaxial on veins. Spore wall surface rugate, foveolate. 2n = 160.

Damp areas in coniferous forests; 300-2900 m. Heilongjiang, Jilin, Liaoning, Nei Mongol, Shaanxi, Shanxi, Xinjiang [Japan, Korea; Europe, North America].

American Gymnocarpium dryopteris is an allotetraploid species that arose following hybridization and polyploidization between G. disjunctum (Ruprecht) Ching and G. appalachianum Pryer & Haufler.

Sarvela noted that a specimen of Gymnocarpium dryopteris from Japan was indusiate; the indusia were reniform, ca. 0.5 mm in diam., hyaline, glabrate, erose at margin. It may be an example of atavism.