153. Polystichum formosanum Rosenstock, Hedwigia. 56: 338. 1915.
台湾耳蕨 tai wan er jue
Polystichum iriomotense Tagawa; P. obtuso-auriculatum Hayata.
Plants evergreen. Rhizome ascending, short, up to 2 cm in diam. including stipe bases, rhizome apex and stipe base densely scaly; scales brown, lanceolate, up to 4 mm, membranous, with few fine teeth, acuminate. Fronds 30-50 cm; stipe pale greenish stramineous, 9-22 cm, ca. 1 mm in diam. at base, above base glabrous. Lamina 1-pinnate, light green on both surfaces when dry, narrowly elliptic-lanceolate, 17-30 × 3.5-7.5 cm at middle, 2.5-4 cm wide at base, gradually or slightly contracted toward base, base broadly rounded-cuneate or nearly truncate, apex abruptly contracted and acuminate; rachis pale greenish stramineous, without proliferous bulbils; costa scaly abaxially; scales dark brown, linear, entire. Pinnae 15-20 pairs, alternate or nearly opposite, approximate by a distance wider than pinna width, attached at right angles to rachis or slightly ascendant, falcate or falcate-lanceolate, middle pairs 1.5-4 cm, 0.5-1.5 cm wide at base, bases asymmetrical, acroscopic base with deltoid or semicircular auricles, and proximal margins of auricles nearly parallel to rachis or often overlapping rachis, basiscopic margins of pinnae narrowly cuneate, often ± recurved, margins irregularly biserrate or toothed, teeth mostly long spinulose apically, apices shortly acuminate; abaxially sparsely covered with microscales; microscales dark brown, ciliate or not, with dilated bases, apices gland-shaped; frond texture leathery; venation distinct on both surfaces, pinnate, lateral veins pinnate, dichotomous or simple, rarely trifurcate, veinlets nearly reaching tips of teeth. Sori small, located on upper lamina, lower pinnae sterile, in 1 row on each side of midrib, medial or close to margins, terminal on shorter veinlets; indusia present, small, irregularly erose, caducous.
Cliffs by streams, mossy rocks, mountains at low elevations; 400-1400 m. Taiwan [S Japan (Ryukyu Islands)].