棕鳞铁角蕨 zong lin tie jiao jue

Asplenium indicum Sledge var. yoshinagae (Makino) Ching & Wu; A. planicaule E. J. Lowe var. yoshinagae (Makino) Tagawa; A. tibeticum Ching; Tarachia yoshinagae (Makino) H. Itô.

Plants 20-45 cm tall. Rhizome erect, short, scaly; scales dark to reddish brown, narrowly triangular, entire, apex acuminate. Fronds caespitose; stipe grayish brown or grayish green to stramineous, 10-20 cm, adaxially grooved longitudinally, with small scales similar to rhizome scales, subglabrous when old; lamina narrowly triangular, 12-30 × 4-7 cm, apex acuminate, 1-pinnate; pinnae 8-20 pairs, alternate or lower ones opposite, shortly stalked, basal pinnae not or slightly reduced, middle pinnae 2-3.5 × 1-1.3 cm, rhomboid to trapezoid or subdimidiate, ± falcate, base asymmetrical, first acroscopic lobe much larger than first basiscopic lobe, acroscopic side truncate, almost parallel to rachis and auriculate, basiscopic side narrowly cuneate (1/4-1/3 cut off) to almost parallel to costa, margin irregularly bicrenate, apex acute to acuminate, rarely obtuse. Veins obvious, grooved adaxially, basal acroscopic vein multi-forked, other veins 1- or 2-forked. Fronds subleathery, grass-green to stramineous when dry, adaxially with wrinkles above veins, small, brown, narrowly triangular and apically filiform scales on abaxial surface and pinna stalks, subglabrous when old; rachis (when dry) abaxially grayish castaneous to green-stramineous for most of its length, and with small narrowly triangular and apically filiform scales, adaxially longitudinally valleculate, gemmae or juvenile plants near rachis on pinna stalks. Sori linear, 4-8 mm, from near costa running nearly to margin, distal sori close to rachis; indusia grayish brown, linear, entire, opening toward costa or first acroscopic vein. Spores with lophate (costate) perispore, average exospore length 36-40 µm. Plants sexual octoploid: 2n = 288.

On wet rocks or tree trunks; 600-2500 m. Fujian, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Sichuan, Xizang, Yunnan, Zhejiang [India, Japan, Vietnam].

Asplenium yoshinagae is a sexual octoploid plant in S India (Kuriachan in Fabbri, Caryologia 18: 675-731. 1965), Japan (Shimura & Takiguchi, J. Jap. Bot. 54: 311-318. 1979), and China (Guangdong, Guangxi, Xizang, and Yunnan). It is morphologically very variable and similar to A. indicum (see above). In China, A. yoshinagae is usually a larger and more vigorous plant with larger spores and stomata than A. indicum. They can easily be distinguished by a chromosome count or by flow-cytometry. The presence of gemmae is a highly unreliable character, at least in China, where most octoploids checked were not gemmiferous. Due to confusion among these taxa, the exact distribution of this species is not well documented.

Asplenium tibeticum, only known from the type collection from Xizang, has leathery fronds morphologically almost intermediate between A. yoshinagae and A. gueinzianum; however, its long slender stipe scales and epidermal and soral cell patterns agree with those of A. yoshinagae, and its average exospore length of 40 µm also fits for this taxon.