193. Polystichum deltodon (Baker) Diels in Engler & Prantl, Nat. Pflanzenfam. 1(4): 191. 1899.
对生耳蕨 dui sheng er jue
Aspidium deltodon Baker, Gard. Chron., n.s., 14: 494. 1880; Hemesteum deltodon (Baker) H. Léveillé; Polypodium submarginale Langsdorff & Fischer; Polystichum deltodon (Baker) Diels var. cultripinnum W. M. Chu & Z. R. He; P. pseudodeltodon Ching & Z. Y. Liu (1984), not Tagawa (1937).
Plants evergreen. Rhizome ascending to erect, short, together with stipe base 1-2 cm in diam., rhizome apex and basal stipe densely scaly; scales brown to dark brown, ovate or ovate-lanceolate, up to 6 × 2 mm, thickly membranous, subentire, acuminate. Fronds 13-42 cm; stipe stramineous, 3-16 cm, 0.5-1.5 mm in diam., stipe above base sparsely scaly; scales brown to dark brown, ovate-lanceolate or ovate, varying in size, membranous, with sparse long teeth, caudate and long acuminate, evanescent; remnant scales mostly appressed. Lamina light green or light brownish green when dry, lanceolate or narrowly elliptic-lanceolate, 9-30 × 2-4.5 cm at middle, base not or slightly contracted, 1-pinnate, apex pinnatifid and acuminate; rachis stramineous, without proliferous bulbils, sparsely scaly on both surfaces; scales brown to pale dark brown, ovate, membranous, with sparse long teeth, caudate. Pinnae 18-40 pairs, often alternate, rarely nearly opposite, contiguous, lower pairs remote, often attached at nearly right angles with rachis, sometimes upper pairs slightly angled acroscopically, sometimes most pinnae or those below middle of lamina slightly angled basiscopically, oblong or falcate-oblong, middle pairs 8-22 × 4-10 mm at base, apices slightly curved upward, acute and shortly spinulose, bases asymmetrical, acroscopic base auriculate; auricles deltoid or nearly deltoid, apex of auricles acute or acuminate and shortly spinulose, proximal margins of auricles truncate or slightly curved, entire or with 1 or 2 shallow obtuse teeth, parallel to rachis or slightly overlapping with rachis, distal margins of auricles often with 1 or 2 shallow incised rounded teeth or sometimes acute coarse teeth; acroscopic margins of pinnae truncate or slightly recurved and crenate, basal basiscopic margins narrowly cuneate, straight, margins entire, distal basiscopic margins curved upward, with coarse and often shortly spinulose teeth; adaxially glabrous, abaxially sparsely covered with narrowly lanceolate light brown microscales; frond texture papery; venation slightly distinct abaxially, distinct adaxially, pinnate; lateral veins pinnate above midrib from base to apex, dichotomous or simple, simple or dichotomous below midrib, sterile veinlets reaching base of teeth. Sori small, terminal on veinlets, close to pinna margin, often in 1 row above midrib, up to 10, only 1-3 below midrib on apical part or none; indusia present, brown, erose, caducous. Spores reniform in equatorial view; perispore sculpturing plicate with granules and perforations.
● Acidic or basic soils in limestone crevices or limestone walls in broad-leaved evergreen forests; 1000-2600 m. Chongqing, Guizhou, Hubei, Hunan, Sichuan, Yunnan.
Polystichum pseudodeltodon from Taiwan is a distinct species, not closely related to P. deltodon. The distribution of P. deltodon in Anhui, Taiwan, and Zhejiang, as well as Japan, Myanmar, and the Philippines, is doubtful.