刺头复叶耳蕨 ci tou fu ye er jue

Polypodium aristatum G. Forster, Fl. Ins. Austr. 82. 1786; Arachniodes carvifolia (Kunze) Ching; A. exilis (Hance) Ching; A. fengyangshanensis Ching & C. F. Zhang ex Y. T. Hsieh; A. lushanensis Ching; A. maoshanensis Ching; A. michelii (H. Léveillé) Ching ex Y. T. Hsieh; Aspidium aristatum (G. Forster) Swartz; A. carvifolium Kunze; A. exile Hance; Byrsopteris aristata (G. Forster) C. V. Morton; Dryopteris aristata (G. Forster) Kuntze; D. carvifolia (Kunze) C. Christensen; D. michelii H. Léveillé; Lastrea aristata (G. Forster) T. Moore; Nephrodium aristatum (G. Forster) C. Presl; Polystichopsis aristata (G. Forster) Holttum; Polystichum aristatum (G. Forster) C. Presl; P. carvifolium (Kunze) C. Christensen; Rumohra aristata (G. Forster) Ching; R. carvifolia (Kunze) Ching.

Rhizome long creeping, 5-8 mm in diam., stiff, densely scaly; scales reddish brown, linear-subulate, ca. 5 × 1 mm, base remotely fimbriate, apex attenuate or filiform, and firmly membranous. Fronds remote, 40-80 cm; stipe 21-40 cm, 2-3 mm in diam., base with dense scales similar to those on rhizome, upward with appressed filiform scales; lamina 3-pinnate(-pinnatifid), shiny green or brownish when dried, ovate-pentagonal or deltoid-pentagonal, 20-35 × 14-25 cm, papery or leathery, base cuneate or subtruncate, apex abruptly narrowed and elongated acute, rachis scaly as distal portion of stipe; pinnae (3 or)4-6(-10) pairs, alternate, with 0.5-1.2 cm stalk, obliquely spreading; lowest pinnae deltoid, 12-18 × 8-12 cm, base broadly cuneate, apex caudate-acuminate; primary pinnules 15-22 pairs, basal basiscopic 1 or 2(-4) and acroscopic 1(-3) elongated (to ca. 12 × 3 cm and shortly stalked), distally abruptly shortened and subsessile; secondary pinnules deltoid-oblong, ca. 1.5 × 0.7 cm, base acroscopically truncate and auriculate, basiscopically cuneate, apex acute, margin serrate to deeply pinnatifid, aristate; upper 1 or 2 pairs of pinnae with at least basal pair of pinnules elongated and pinnatifid to pinnate; remaining pinnae deltoid-lanceolate or linear-lanceolate; axes and veins of ultimate segments with minute brown linear-subulate scales abaxially. Sori terminal on veinlets, 5-8 pairs per ultimate pinnule, medial between midvein and margin; indusia brown, membranous, entire or shortly ciliate. 2n = 82*.

Broad-leaved forests, wet ravines along streams, sometimes under cypress forests or other coniferous forests; 100-1600 m. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Henan, Hunan, Jiangsu, Jiangxi, Shandong, Taiwan, Zhejiang [India, Japan, Korea, Malaysia, Nepal, Philippines; Australia, Pacific islands].

In China, this fern is distinguished by its long-creeping rhizome with fronds arising at remote intervals and its lamina abruptly narrowed toward apex and acuminate. However, fronds with a gradually acuminate apex, including those of the type specimen, are occasionally found from other countries. Whether it is reasonable to use Arachniodes exilis for the Chinese ferns still needs further comparison.