北京铁角蕨 bei jing tie jiao jue

Asplenium abbreviatum Makino; A. sarelii Hooker subsp. pekinense (Hance) Fraser-Jenkins, Pangtey & Khullar; A. sarelii var. pekinense (Hance) C. Christensen; A. sepulchrale Hooker.

Plants 3-20 cm tall. Rhizome erect, short, apex scaly; scales dark brown to black, triangular, 1-5(-8) × 0.3-0.7 mm, scale base with numerous yellow-brown, unicellular hairs 1-5 × ca. 0.02 mm, similar to root hairs, apical part subentire, acuminate. Fronds caespitose; stipe green, 2-8(-10) cm, semiterete to terete, base densely scaly, with reduced hairlike scales toward rachis or subglabrous, adaxially sulcate with pronounced supravascular ridge; lamina lanceolate to narrowly ovate-trullate, 5-15 × 1.5-4 cm, base often gradually reduced, 2-pinnate to 3-pinnatifid, apex acute; pinnae 6-12 pairs, lower pinnae often reduced, 1-2.5 cm, stalk 0.5-1.5(-2) mm, adaxially sulcate and with distinct supravascular ridge; basal pinnae remote, opposite, often flabellate to deltoid-triangular, apex obtuse to acute, base symmetrical, truncate, 2-pinnate, with 2-4 pinnule pairs, basal pinnules nearly parallel to rachis; middle pinnae often largest, triangular-ovate, base asymmetrical, pinnate to bipinnatifid with 2-4 pairs of pinnules, basal pinnules largest, 5-8 × 2-4 mm, pinnatisect with 1 or 2 pairs of narrowly cuneiform to sublinear segments, 0.5-2 mm wide, apex subacute to truncate with 2 or 3 acute, 0.5-1 mm teeth. Costa sulcate adaxially, with distinctly raised median supravascular ridge, veins obvious, raised adaxially, flabellately anadromous, not reaching margin. Fronds firmly herbaceous, dark green to grayish green when dry, lamina subglabrous, average stomatal guard cell length 45-52 µm; rachis and costa green, semiterete, adaxially sulcate and with prominent median supravascular ridge, with black fibrillar scales or subglabrous. Sori 1 or 2(-4) per pinnule, often spreading at maturity, subelliptic to linear, 1-2 mm; indusia white-gray, subelliptic, membranous, margin irregularly sinuate, opening toward costa or costule, persistent. Spores brown with lophate (costate) perispore, average exospore length 34-38 mm. Plants autotetraploid: 2n = 144.

In rock crevices, on buildings and walls; 100-3900 m. Anhui, Chongqing, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hebei, Henan, Hubei, Hunan, Jiangsu, Liaoning, Nei Mongol, Ningxia, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [India, Japan, Korea, Pakistan, Russia (E Siberia)].

Asplenium pekinense is an autotetraploid (Mitui, J. Jap. Bot. 40: 117-124. 1965; Lin & Sleep in K. H. Shing & K. U. Kramer, Proc. Int. Symp. Syst. Pterid. 111-127. 1989; Wang, Acta Bot. Sin. 45: 1-14. 2003) species arisen by chromosome doubling in diploid A. sarelii. Allotetraploid A. anogrammoides is very similar because true A. sarelii is one of its ancestors, the second being A. tenuicaule (Lin & Sleep, loc. cit.). Reticulate hybridizations between diploid A. tenuicaule, A. sarelii, and A. semivarians led to the evolution of many confusingly similar taxa defying description. These can be grouped into the A. pekinense-complex consisting of A. altajense, A. anogrammoides, A. pekinense, and A. sarelii, and the A. varians group containing A. aitchisonii, A. kukkonenii, A. semivarians, and A. varians. Their close relationship and similarity has led to many wrong identifications, as well as incorrect and unreliable citations. In many places where A. pekinense grows with A. anogrammoides, their sterile tetraploid hybrid is relatively common. Asplenium ×kidoi Sleep ex Viane, Y. X. Lin & Reichstein, nothosp. nov. Type: China. Hebei: ca. 20 km NW of Beijing, Xiangshan park, natural pine forest above Fragrant Hill Hotel, among grasses on shaded hillside with A. anogrammoides, A. pekinense, and Athyrium niponicum (Mettenius) Hance, 190 m, 27 Sep 1997, Viane 7047 (holotype, GENT). Planta hybrida, inter parentes A. anogrammoides et A. pekinense quoad divisionem laminae atque pinnularum segmentorumque formam necnon dimensiones cellularum accessoriarum stomatum intermedia, ab eis sporis abortivis necnon chromosomatum numero tetraploideo (2n = 144, meiose trivalentium bivalentium univalentiumque numeris valde irregularibus) differt. This morphologically intermediate plant often shows hybrid vigor; it was first studied by A. Sleep (a.o., in Lin & Sleep, loc. cit.) who collected it in Japan (Kyushu: Ashi-Kita-cho, 1 Nov 1968, A. Sleep & M. Kido AS/605; BM, PE, TI, Z).

Z. R. Wang and K. Q. Wang (Acta Bot. Sin. 45: 8. 2003) reported a hybrid between Asplenium pekinense and A. exiguum (as A. yunnanense), "A. ×jingyunense," and one between A. pekinense and A. varians, "A. ×longmenense," but the two names were not validly published because no Latin description or diagnosis, or reference to such, was provided (Melbourne Code, Art. 39.1).