网脉铁角蕨 wang mai tie jiao jue

Asplenidictyum finlaysonianum (Wallich ex Hooker) J. Smith; Hemidictyum finlaysonianum (Wallich ex Hooker) T. Moore.

Plants 30-50 cm tall. Rhizome erect, short, scaly; scales dark brown, narrowly triangular, entire. Fronds caespitose; stipe grayish green or stramineous, 15-26 cm, with scales similar to those on rhizome, toward rachis with paleasters or subglabrous; lamina ovate-elliptic, 20-32 × 10-22 cm, 1-pinnate; pinnae 2-6(-9) pairs, shortly stalked, lower pinnae not (much) reduced, ovate-lanceolate, 7-12 × 2-3.6 cm, base cuneate, gradually decurrent on stalk, margin entire to repand, apex acuminate and sometimes gemmiferous; terminal pinna similar to lateral ones but usually wider and more rhombic or hastate, 8-15 × 5-11 cm, its base often 3-lobed. Venation subflabellate with indistinct costa, veins faintly visible, almost parallel, ± anastomosing near margin. Frond papery or subleathery, brownish green when dry, with small scales along rachis and costa, becoming glabrous when old; rachis stramineous to grayish green, with sparse small narrowly triangular scales. Sori linear, variable in length, 5-45 mm, usually on acroscopic side of acroscopic veins; indusium yellowish to brown, linear, papery, entire, opening toward costa. Plants sexual polyploid: 2n = 144 or 288.

On wet rocks or tree trunks in dense forests; 700-1100 m. Guangdong, Guangxi, Hainan, Xizang, S Yunnan [Bhutan, India, Indonesia, Malaysia, Myanmar, Nepal, Vietnam].

Asplenium finlaysonianum is a Himalayan species with a typical morphology and venation pattern unlike any other taxon in the family. Though Bir (Curr. Sci. 29: 445-447. 1960) published a chromosome count showing this is a tetraploid (n = 72) in Sikkim, India, we found an octoploid plant in N Myanmar. The cytology of the Chinese plants is not known.