镰叶铁角蕨 lian ye tie jiao jue

Asplenium adiantoides (Linnaeus) C. Christensen (1905), not Lamarck (1786), nor Raddi (1819), nor Raoul (1844); A. falcatum Lamarck; A. lofouense Christ; A. longjinense Ching & S. H. Wu; Tarachia falcata (Lamarck) C. Presl; Trichomanes adiantoides Linnaeus.

Plants 20-60(-90) cm tall. Rhizome shortly creeping to erect, scaly; scales dark brown, narrowly triangular with filiform apex, entire. Fronds caespitose; stipe dull or semi-shiny, grayish brown, 10-35(-45) cm, scaly at base, upward subglabrous, semiterete and adaxially grooved; lamina oblong to elliptic, 10-35(-45) × 8-16 cm, pinnate; pinnae (2-)5-10(-15) pairs, opposite or subopposite, distinctly stalked, lower pinnae not or only slightly reduced, median pinnae 4-10(-15) × 1.2-2.2(-2.8) cm, rhomboid to broadly lanceolate, ± falcate, base nearly symmetrical, cuneate, acroscopic side sometimes subauriculate, basiscopic side narrowly cuneate, margin serrate often with long teeth, apex acuminate, terminal pinna conform with lateral pinnae but often wider than subapical ones or with ascending pinnalike lobes at its base, 5-11 × 2-5(-10) cm. Costa abaxially flat to slightly raised, adaxially with a longitudinal furrow (grooved). Veins prominent, several times forked, subflabellate, almost parallel, reaching margin. Frond (sub)leathery, dark brown when dry, pinna stalk and base with small dark brown scales becoming subglabrous when old; rachis dark gray-brown, semiterete and adaxially grooved. Sori linear, 1-3 cm, on acroscopic veins; indusia brown, linear, entire, opening toward costa. Plants sexual polyploid: 2n = 144, 216, or 360.

On rocks along streams or in forests; sea level to 800 m. Guangdong, Guangxi, Guizhou, Hainan, Taiwan, SE Yunnan [India, Indonesia, Malaysia, Myanmar, Philippines, Sri Lanka, Vietnam; tropical Africa, Australia, Indian Ocean islands, Pacific islands (including New Zealand)].

Asplenium polyodon is a widespread and variable aggregate species that needs more study before it can be split. Tetraploid chromosome numbers were reported from Australia, India (Darjeeling), Malaysia, New Zealand, and Sri Lanka. We found tetraploids and hexaploids in Uganda and China (Guangxi), and decaploids in Réunion and China (Hainan). Plants with broad pinnae have once been identified as A. macrophyllum Swartz (in Schrader, J. Bot. 1800(2): 52. 1801), but the difference between this species and A. polyodon requires further study.