草山耳蕨 cao shan er jue

Plants evergreen. Rhizome erect or ascending, short, densely covered with linear grayish brown scales. Fronds up to ca. 80 cm; stipe yellowish brown, 24-34 cm, 3-4 mm in diam. at base, densely covered with linear, lanceolate, yellowish brown scales and larger scales; large scales shiny, ovate and ovate-lanceolate, up to 8 × 6 mm, with dense small teeth, caudate. Lamina bipinnate, oblong-lanceolate, up to 63 × 17 cm at middle, not contracted toward base, lower part sterile, apex acute, fertile; rachis without proliferous bulbils, abaxially covered with linear, lanceolate, grayish brown scales and larger scales; large scales dense, shiny, ovate, ovate-lanceolate, and narrowly lanceolate, up to 10 × 4 mm, with dense small teeth, caudate or long acuminate. Pinnae up to 32 pairs, alternate, slightly ascendant, shortly stalked, lanceolate, gradually contracted toward basiscopic base, bases asymmetrical, apices acuminate or caudate; middle pinnae ca. 12 × 1.3 cm, 1-pinnate; costa adaxially sulcate, densely covered with linear light brown scales. Pinnules up to 23 pairs, alternate, shortly stalked, narrowly deltoid-ovate, 0.6-1 × 0.3-0.4 cm, bases cuneate, acroscopic margins slightly repand, with deltoid auricles, basiscopic margins obviously spinulose, apices acute with acute tips; basal acroscopic pinnules largest, deeply incised; both surfaces densely covered with long-filiform light brown microscales; frond texture papery; venation pinnate, lateral veins 4-6 pairs, dichotomous, distinct. Sori 2-5 per pairs pinnule, in 1 row on each side of midrib, terminal on veinlets; indusia present, entire.

● Forests; 500-800 m. Taiwan.

Polystichum sozanense is often not accepted, but its stipe and rachis scales are much wider than P. parvipinnulum. It is possible that this species is extinct. More studies are needed.