中越耳蕨 zhong yue er jue

Aspidium aculeatum (Linnaeus) Swartz var. tonkinense Christ, Bull. Sci. France Belgique 28: 268. 1898.

Plants evergreen. Rhizome ascending, short, together with remnant stipe base 2-3 cm in diam. Fronds few, 35-105 cm; stipe stramineous, 12-60 cm, 2-3 mm in diam. at base, whole stipe to rachis with numerous scales, scales appressed, dark brown, ovate, membranous, entire, acute, evanescent. Lamina bipinnate, green when dry, adaxially darker, ovate or ovate-lanceolate, 18-47 × 7-23 cm at middle, slightly or not contracted at base, broadly cuneate, acuminate; rachis stramineous, without proliferous bulbils. Pinnae 10-15 pairs, alternate or opposite, slightly ascendant, sometimes basal pairs attached at nearly right angles to rachis, slightly shortly stalked, narrowly oblong or falcate-lanceolate, 2-15 × 1-3 cm, bases broadly cuneate, symmetrical on both sides, apices often acute or shortly acuminate, rarely long acuminate; costa stramineous, lower part often without narrow green wings, with conspicuous narrow green wings upward, adaxially glabrous, abaxially sparsely scaly; scales dark brown or reddish brown, ovate or narrowly ovate, membranous, margins entire, apices caudate and long acuminate, upper part not appressed. Pinnules 3-17 pairs, oblong or oblong-ovate, alternate, approximate, slightly ascendant, 0.5-2 cm × 3-8 mm, bases cuneate and decurrent forming narrowly winged stalk, bases asymmetrical, acroscopic base wider, slightly auriculate, basiscopic margins narrowly cuneate, margins pinnatilobate to pinnatipartite, apices acuminate. Lobes 2-5 pairs, ascendant, often ovate-deltoid, rarely clavate-oblong, apices acute, often with curved upward and short spinules, often not lobed, margins entire, rarely lobed and forming 2 or 3 lobules; lobules coarsely toothed; adaxially glabrous, abaxially sparsely scaly; microscales brown, lanceolate; frond texture papery; venation slightly distinct on both surfaces, pinnate, lateral veins pinnate to forked from base to apex on acroscopic lobes, simple on lobe apex, not reaching lobe margins. Sori small, ca. 1 mm in diam., terminal on veinlets, medial or nearly medial on acroscopic part of pinnules (between midrib and margins); indusia present, brown or dark brown, thickly membranous, entire, evanescent. Spores semicircular in equatorial view, perispore sculpturing plicate.

Limestone hills, rocks in broad-leaved evergreen forests; 800-1500 m. Guangxi (Napo), Guizhou (Libo), Yunnan (Jinping, Xichou) [N Vietnam].

Polystichum tonkinense is similar to P. excelsius, but its pinnae are often acute (rarely acuminate) apically, its costa does not have green wings, its pinnules are approximate, larger, often 1-2 cm, and wider than 5 mm, the spinules of its lobe apex are shorter or inconspicuous, and its sori are medial or nearly medial.