阿尔泰铁角蕨 a er tai tie jiao jue

Asplenium sarelii Hooker ["saulii"] f. altajense Komarov, Izv. Imp. Bot. Sada Petra Velikago 16: 150. 1916; A. chingianum Chang Y. Yang.

Plants 5-15 cm tall. Rhizome erect, short, apex scaly; scales dark brown to black, narrowly triangular, 2-3.5 × 0.3-0.5 mm, entire. Fronds caespitose; stipe 2.5-3.5(-6) cm, base scaly and brown abaxially, green upward, adaxially green, sulcate, subglabrous; lamina 2-pinnatifid to 2-pinnate, narrowly triangular-ovate, 8-9 × 2-2.5 cm, base slightly reduced, apex acute; pinnae (5-)10-15 pairs, lower pinnae subopposite, often deltoid-flabellate or almost orbicular, upper alternate and gradually fused into 0.5-1 cm pinnatifid apex, second to fourth pair usually largest, stalk up to 1 mm and adaxially sulcate with raised supravascular ridge, middle pinnae triangular-ovate, ca. 11 × 8-10 mm, base asymmetrical, acroscopic side truncate, basiscopic side cuneate, 1-pinnate, apex obtuse; pinnules 2 or 3 pairs, anadromous, basal acroscopic pinnule free, largest, subovate, 4-5 × 2-4 mm, base cuneate, other pinnules adnate to costa and confluent into pinna apex, margins dentate-serrate, apex obtuse. Veins obscure, flabellately anadromous, slightly raised adaxially. Fronds papery, green to grayish green when dry, lamina subglabrous, average stomatal guard cell length 44-48 µm; rachis semiterete, green, adaxially sulcate and with raised supravascular ridge. Sori 2-4 per pinnule, basal to medial on pinnae, at maturity confluent, linear-elliptic, 1-2.5 mm; indusia grayish green, linear-elliptic, membranous, entire, opening toward costa or costules. Spores with lophate (cristate) perispore, average exospore length 32-34 µm. Plants sexual, allotetraploid: 2n = 144.

In crevices of shaded rocks; 400-1500 m. Nei Mongol, Ningxia, Sichuan, Xinjiang [Mongolia, Russia (Altai, S Siberia)].

Asplenium altajense is relatively common in the area bordering China, the Altai Mountains, Mongolia, and Russia, but future research will have to show if the area given by Grubov (Rast. Tsentral. Azii 1: 82. 1963) is correct. In general shape, this taxon is similar to A. pekinense Hance. However, most pinnae of A. altajense have only the basal acroscopic pinnule free, the others are confluent and form the pinna apex, while in A. pekinense several segments are free or just slightly adnate to the costa. The stipe is less scaly in A. altajense, and its texture is more herbaceous. Asplenium altajense is also similar to A. tenuicaule, from which it can be distinguished by the more narrow and acute teeth (obtuse to mucronate in A. tenuicaule). Due to confusion between A. tenuicaule, A. pekinense, and A. anogrammoides, the distribution of this taxon is not well known. Asplenium chingianum (type fragment in IBSC!) is a submature plant with immature sporangia, few and unripe spores, and almost no scales; it is also similar to A. nesii specimens from N Pakistan. The hybrid between A. altajense and A. tenuicaule is relatively common where they grow together.