匙形铁角蕨 shi xing tie jiao jue

Asplenium spathulinum J. Smith ex Kunze (1848).

Plants 30-65 cm tall. Rhizome erect or ascending, scaly; scales brown, narrowly triangular, margins subdentate. Fronds caespitose; stipe dull grayish brown to gray-green, semiterete, 13-30 cm, subglabrous, adaxially sulcate; lamina triangular to ovate, 21-36 × 10-20 cm, not much reduced at base, apex acute-acuminate, bipinnate; pinnae 12-18 pairs, subopposite to alternate, stalks 2-3 mm, basal pinnae largest or slightly reduced, narrowly triangular, 7-14 × 3.5-4.5 cm, apex variable, from acute to caudate, 1-pinnate; pinnules 4-8 pairs, anadromous, free to subsessile, from ovate-elliptic to rhombic or cuneiform, apex obtuse, basal acroscopic pinnule ± equal to basal basiscopic pinnule, basal pair largest, 1.5-3 × 1-1.3 cm, base nearly symmetrical, cuneate, distal segments decurrent on rachis, lateral sides entire, outer margin dentate to crenate. Costa obvious on both sides, raised abaxially, adaxially shallowly grooved with raised supravascular ridge, veins 2- or 3-forked and not reaching margin. Fronds herbaceous, brownish green when dry, subglabrous; rachis grayish brown to gray-green, adaxially sulcate, apical part of rachis often gemmiferous. Sori 1-4 per pinnule, not reaching margin, linear, 5-10 mm; indusia brownish, linear, membranous, entire, opening toward costa or costule, persistent.

Epiphytic in forests; 600-1400 m. Hainan [Indonesia, Malaysia, Philippines, Sri Lanka; Mascarene Islands].

Hooker’s name, Asplenium spathulinum, has often been used to describe this variable taxon (e.g., Beddome, Ferns S. India, t. 226. 1864; Tardieu & Ching, Notul. Syst. (Paris) 5: 134-154. 1936; Holttum, Revis. Fl. Malaya 2: 439. 1954; Copeland, Fern Fl. Philipp. 3: 445. 1960; Chun et al., Fl. Hainan. 1: 116. 1964; S. H. Wu, FRPS 4(2): 70. 1999; T. L. Wu et al., Fl. Guangdong 7: 198. 2006). Manton and Sledge (Philos. Trans., Ser. B, 238: 127-185. 1954) showed that A. affine is an aggregate of an octoploid and a dodecaploid species (S India and Sri Lanka). Plants from closer to the type locality of Mauritius, in Réunion, were dodecaploid. Because specimens from the Hainan populations have the same ploidy level (12x), we use the name A. affine following Sledge’s (Bull. Brit. Mus. (Nat. Hist.), Bot. 3: 235-277. 1965) concept, based on morphological and cytological study. Mature A. affine plants can be very similar to juvenile specimens of A. pseudolaserpitiifolium and its relatives.