42. Athyrium oppositipennum Hayata, J. Coll. Sci. Imp. Univ. Tokyo. 30: 441. 1911.
对生蹄盖蕨 dui sheng ti gai jue
Athyrium oppositipennum var. pubescens (Tagawa) Yea C. Liu, W. L. Chiou & H. Y. Liu; A. oreopteris Copeland; A. taiwanense Tagawa; A. taiwanense var. pubescens Tagawa; Dryopteris oppositipenna (Hayata) Hayata.
Rhizomes short, erect, apex densely scaly; scales lanceolate, blackish brown in center, brown in marginal part. Fronds caespitose; fertile fronds 60-80 cm; stipe brown-stramineous at base, 30-40 cm, 3.5-5 mm in diam., base similarly scaly; lamina 2-pinnate, oblong or oblong-lanceolate, 35-45 × 20-25 cm, base not narrowed, apex acuminate; pinnae 12-15 pairs, basal pinnae opposite, upper pinnae alternate, subspreading, sessile; lower pinnae linear-lanceolate, 15-20 × 2-2.5 cm at middle, base truncate, slightly overlaying rachis, pinnate-pinnatifid, apex caudate; pinnules 26-35 pairs, opposite or subopposite, usually recurved or slightly spreading, distal pinnules ascending; middle pinnules linear-lanceolate, 11-15 × ca. 4 mm, base rounded-truncate and adnate to costae, somewhat auriculate on acroscopic side, somewhat decurrent on basiscopic side, pinnatilobate, apex acute or obtuse; pinnule segments ca. 5 pairs, subsquare, ascending, with 2-4 broadly triangular teeth at apex, usually basal acroscopic segments larger; veins somewhat visible adaxially, visible abaxially, pinnate in pinnules, lateral veins 6-9 pairs, oblique, often forked in upper segments. Lamina thickly papery when dried, dark brown adaxially, greenish brown abaxially, glabrate on both surfaces. Rachis and costae brownish stramineous, glabrate abaxially, with subulate spines at base of costae and costules on adaxial side. Sori elliptic, usually 1 per segment, biseriate on both sides of costule; indusia dark brown, elliptic, membranous, erose at margin. Perispore surface without folds. 2n = 120* (3× apomictic).
● Valley forests, bamboo grasslands, sometimes in shaded wet areas; 1800-3000 m. Taiwan.