6. Hymenasplenium szechuanense (Ching) Viane & S. Y. Dong
天全膜叶铁角蕨 tian quan mo ye tie jiao jue
Basionym: Asplenium szechuanense Ching, Acta Phytotax. Sin. 10: 188. 1965.
Plants 25-40 cm tall. Rhizome long creeping, 1.5-2.5 mm in diam., apex scaly; scales dark brown to blackish, narrowly triangular to triangular. Fronds remote, up to 13 mm apart, green to brownish dark green when dry, herbaceous, subglabrous; stipe shiny, dark purplish, 7-15 cm, base with narrow scales similar to those on rhizome, with brownish indument or subglabrous; lamina 1-pinnate, narrowly oblong-triangular, 15-25 × 3-5 cm, base truncate, apex acuminate to caudate; rachis shiny and purple to castaneous-purple, subglabrous; pinnae 20-25 pairs, almost sessile and color of rachis entering stipicel and base of costa abaxially, trapeziform to trapeziform-lunate, middle pinnae 1.5-2.3 × 0.7-1 cm, dimidiate, apex truncate to obtuse, base asymmetrical, acroscopic side truncate and parallel to rachis, basiscopic side cut away and narrowly cuneate and entire, acroscopic margin coarsely crenate-serrate with retuse teeth; pinnae erect, basal pinnae slightly reduced. Veins distinct, forking and free, each vein ending below a marginal notch, basiscopic side with 3 or 4 veins lacking. Sori inframedial, elliptic, 3-4.5 mm; indusia persistent, brown, semi-elliptic, membranous, entire, opening toward costa.
● On rocks by streams. Sichuan, Yunnan.
Hymenasplenium szechuanense is similar to H. furfuraceum from which it differs in its much less floccose to subglabrous rachis and stipe, its inframedial sori, and its more reddish purple rachis. It differs from H. quercicola in its inframedial sori and more dark purple stipe. Hymenasplenium latidens is also similar but differs by the characters given in the key and by its slightly more numerous pinna pairs; future research will have to show their relationship. All these taxa also resemble H. obliquissimum but that species has its veins ending in marginal teeth, not below a notch in a marginal tooth as in this group. Due to confusion with similar taxa, the relationships and the distribution of this species are not well known.