9. Hymenasplenium adiantifrons (Hayata) Viane & S. Y. Dong
阿里山膜叶铁角蕨 a li shan mo ye tie jiao jue
Basionym: Asplenium resectum Smith f. adiantifrons Hayata, Icon. Pl. Formosan. 4: 226. 1914; Asplenium adiantifrons (Hayata) Ching.
Plants 18-40(-45) cm tall. Rhizome long creeping, 1.5-2.5 mm in diam., apex scaly; scales narrowly triangular to triangular. Fronds remote, up to 12 mm apart, green to brownish dark green when dry, herbaceous, subglabrous; stipe shiny, castaneous-purple, 5-20 cm, base with scales similar to those on rhizome or subglabrous; lamina 1-pinnate, narrowly oblong-triangular, 10-25 × 2-5 cm, base truncate and slightly reduced, apex acuminate to caudate; rachis shiny, castaneous-purple; pinnae 20-30 pairs, almost sessile and color of rachis not entering base of stipicel abaxially, trapeziform to slightly lunate, middle pinnae 1.2-2.2 × 0.5-0.7 cm, dimidiate, apex subacute to obtuse, base asymmetrical, acroscopic side truncate and parallel to rachis, basiscopic side cut away and narrowly cuneate and entire, acroscopic margin crenate with retuse teeth; pinnae spreading, basal pinnae slightly reduced and deflexed. Veins distinct, forking and free, each vein ending below relatively shallow marginal notch, basiscopic side with 3 or 4 veins lacking. Sori inframedial, linear, 3-4 mm; indusia persistent, brown, semi-elliptic, membranous, entire, opening toward costa.
● Forests, often on slopes in moist to wet conditions; 1000-2200 m. Taiwan.
Our description of Hymenasplenium adiantifrons differs from Chings, which was solely based on the type and the drawing of Hayata. Although Ching (Acta Phytotax. Sin. 10: 187-188. 1965) compared this taxon essentially to H. latidens, it is morphologically also similar to H. changputungense and H. szechuanense. In the literature (Kurata, J. Geobot. 11: 67-68. 1962; Sugimoto, Keys Herb. Pl. Jap. Pterid. 356, 406. 1966; Nakaike, Enum. Pterid. Jap. 97. 1975), this species has sometimes been synonymized or confused (Taiwan) with H. filipes (Copeland) Sugimoto (Philippines) from which it differs, i.a., by its retuse marginal teeth (entire in H. filipes), its shiny stipe and rachis (almost dull in H. filipes), and spreading pinnae (pointing upward in H. filipes).