东亚膜叶铁角蕨 dong ya mo ye tie jiao jue

Asplenium hondoense N. Murakami & Hatanaka, J. Fac. Sci. Univ. Tokyo, Sect. 3, Bot. 14: 191. 1988.

Plants 25-40 cm tall. Rhizomes shortly creeping, 2-3 mm in diam., apex densely scaly; scales castaneous to dark brown, narrowly triangular; phyllopodia distinct, ca. 2 mm tall, ca. 10 mm apart. Fronds grayish green when dry, herbaceous; lamina 1-pinnate, narrowly triangular to lanceolate, 10-20 × 3-5 cm, widest in basal 1/3, gradually narrowing toward apex, glabrous; stipe shiny, purple, 10-25 × 0.05-0.15 cm, subglabrous, base sparsely scaly; rachis shiny, purplish abaxially, adaxial side grooved and with 2 grayish green narrow wings; pinnae almost sessile to shortly stalked with rachis color extending via stipicel onto base of costa abaxially, 15-25 pairs, alternate, usually ascending, trapeziform to falcate, 2-3.5 × 0.6-1 cm, base asymmetrical, acroscopic side truncate, basiscopic side attenuate-cuneate with 1/3-1/2 cut away, acroscopic margin serrate, teeth not retuse, pinna apex subacute to obtuse. Veins forking and terminating in marginal teeth, 2 or 3(or 4) basal basiscopic veins lacking. Sori linear, 4-5 mm, medial; indusia brownish, linear, membranous, entire, opening toward costa. Plants usually agamosporous.

Usually on wet rocks near streams in forests. Fujian, Guangxi, Sichuan [NE India, Japan, Korea, Nepal].

The distribution of Hymenasplenium hondoense is not well known due to confusion with other members of the genus. As presently circumscribed, this is a cytologically variable, aggregate species. Usually plants are agamosporous diploids ("n" = 2n = 72) or triploids ("n" = 2n = 117), but in China, sexual diploids and tetraploids exist. The elucidation of this aggregate and its relationships to the other SE Asian members of the "unilaterale" group will require more study.