毛轴铁角蕨 mao zhou tie jiao jue

Asplenium beddomei Mettenius ex Kuhn; A. hancei Baker; A. polytrichum Christ; A. saigonense C. G. Matthew & Christ.

Plants 20-40 cm tall. Rhizome erect, short, scaly; scales blackish brown, narrowly triangular to deltoid-tridentate with long apical tail. Fronds caespitose; stipe grayish brown to purplish black, 5-12 cm, semiterete, adaxially grooved, with blackish brown deltoid-tridentate scales with long apical tail; lamina lanceolate to linear-lanceolate, 10-30 × 3.5-8 cm, gradually reduced at base, apex acute, 1-pinnate; pinnae 18-30(-40) pairs, alternate or lower ones (sub)opposite, almost sessile to shortly stalked; basal pinnae slightly reduced, deltoid-triangular to ovate, apex obtuse; middle pinnae narrowly subtriangular to rhomboid-elliptic, 2-4(-5.5) × 0.8-1.5 cm, base asymmetrical, acroscopic side truncate and auriculate, basiscopic side narrowly cuneate, margin irregularly biserrate-crenate, apex acute. Veins obvious, mostly 2-forked, 3-forked, or simple, not reaching margin. Fronds papery, dark brown when dry, both surfaces with dark brown stellate or hairlike small scales, subglabrous when old; rachis grayish brown, semiterete, adaxially grooved, with rigid hairlike scales, rarely with subapical gemma. Sori linear to crescent-shaped, 4-8 mm, on acroscopic veinlets; indusia yellowish brown to grayish brown, linear, membranous, entire, opening toward costa or to first acroscopic vein, often rolling back at maturity, persistent. Perispore costate, with average exospore length 40-44 (dodecaploids). Plants sexual polyploid: 2n = 144, 288, or 432.

On rocks at streamsides, in forests; 100-3000 m. Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hunan, Jiangxi, Sichuan, Xizang, Yunnan [India, Malaysia, Myanmar, Philippines, Thailand, Vietnam; Australia].

Tetraploid plants (n = 72) of Asplenium crinicaule were reported from India (Bir, Curr. Sci. 29: 445-447. 1960), but in China, this is an aggregate of octo- and dodecaploid taxa. At present, octoploids are known from S India (Kuriachan, Cytologia 32: 500-506. 1968), Sichuan (Wang in K. H. Shing & K. U. Kramer, Proc. Int. Symp. Syst. Pterid. 133-134. 1989), Guangdong, and Guizhou, and dodecaploids from Guizhou and Guangdong.

Plants are variable in frond and pinna shape, even at the type locality at Dinghu Shan, Guangdong, where the species is dodecaploid. Members of this aggregate are similar to Asplenium pellucidum Lamarck, which is octoploid in Réunion, but has more narrow pinnae with an acuminate apex and many strongly reduced basal pinnae. Asplenium horridum Kaulfuss has similar scales. We prefer to treat this taxon as an aggregate species until the ploidy of plants at the different type localities is better known.

The name Asplenium adiantoides (here treated as a synonym of A. aethiopicum) was misapplied to this species by Y. C. Wu et al. (Bull. Dept. Biol. Sun Yatsen Univ. 3: t. 88-89. 1932).