43. Polystichum robustum Ching ex Li Bing Zhang & H. S. Kung, Acta Phytotax. Sin. 36: 468. 1998.
粗壮耳蕨 cu zhuang er jue
Plants evergreen. Rhizome erect or ascending, short, densely covered with linear reddish brown scales. Fronds 1-1.5 m; stipe stramineous, 60-75 cm, 7-10 mm in diam. at base, densely covered with linear and lanceolate brown scales and larger scales; large scales grayish brown and bicolorous, broadly ovate and broadly ovate-lanceolate; bicolorous scales dense, middle part dark brown to blackish brown, shiny, up to 18 × 10 mm, shortly serrulate, caudate. Lamina bipinnate, oblong, 66-96 × 24-47 cm at middle, slightly contracted toward base, apex abruptly narrowed, fertile; rachis without proliferous bulbils, densely covered with linear dark brown scales, and sparsely covered with lanceolate grayish brown scales, latter up to 10 × 3 mm, serrulate, acuminate. Pinnae 10-17 pairs, alternate, ascendant, shortly stalked, lanceolate, apices caudate, basiscopic margins slightly contracted toward base, bases asymmetrical, middle pinnae 14-20 × 4.6-5.7 cm, 1-pinnate; costa scaly; scales grayish brown or blackish brown, linear or lanceolate. Pinnules 15-19 pairs, alternate, shortly stalked, deltoid-ovate, 2.1-4 × 0.8-1.6 cm, bases cuneate, acroscopic bases with semi-orbicular auricles, apices acute and mucronate, margins with obtuse teeth, tips of teeth not aristate; basal acroscopic pinnules largest, pinnatipartite; abaxially with lanceolate microscales, adaxially subglabrous; frond texture leathery; venation pinnate on pinnules, lateral veins 8-10 pairs, dichotomous, distinct. Sori numerous per pinnule, in several rows on each side of midrib, terminal on veinlets, sometimes nearly terminal, brown, large; indusia small.
● Evergreen forests; ca. 900 m. NE Yunnan (Suijiang).
Polystichum robustum is the largest in the genus in Asia. It has stipe scales bicolorous, pinnule margins with obtuse teeth, and sori in several rows on each side of the midrib.