55. Asplenium bullatum Wallich ex Mettenius, Abh. Senckenberg. Naturf. Ges. 3: 150. 1859.
大盖铁角蕨 da gai tie jiao jue
Asplenium cavalerianum Christ; A. grandifrons Christ; A. latecuneatum Christ; A. viridissimum Hayata.
Plants 60-100 cm tall. Rhizome erect, apex scaly; scales medium to dark brown, lanceolate, margin subentire. Fronds caespitose; stipe dull gray-brown to gray-green, semiterete, 20-43 cm, adaxially sulcate, base scaly, becoming subglabrous near rachis; lamina triangular-ovate, 45-70 × 18-35 cm, apex acute, 2-pinnate to 4-pinnatifid; pinnae 16-19 pairs, subopposite to alternate, stalked, basal pinnae slightly reduced, middle pinnae largest, narrowly triangular, 11-19 × 4-8 cm, often slightly falcate, apex acuminate, base asymmetrical, acroscopic side truncate, basiscopic side cuneate, 2- or 3-pinnate; pinnules 8-13 pairs, anadromous, basal pinnules free and stalked, distal pinnae adnate to costa, basal acroscopic pinnule largest, ovate-triangular, 2.5-4 × 1.6-2.2 cm, base cuneate, asymmetrical and often decurrent along costule, apex obtuse to subacute; ultimate pinnules 2-5 pairs, basal acroscopic segment largest, ovate, 12-15 × 6-8 mm, apex obtuse to truncate, base cuneate and decurrent on costule or free, margin dentate, teeth deltoid-triangular and often submucronate. Veins obscure, anadromous, rarely simple with distinct terminal hydathode on adaxial side, not reaching margin. Fronds herbaceous, green; rachis gray-green, semiterete, lamina with 2-4 cellular uniseriate hairs with apical gland or subglabrous, adaxially sulcate but with distinct supravascular ridge; costa pale brown to green, terete-semiterete, adaxially sulcate with distinct supravascular ridge, winged near its apex. Sori 1-25 per pinnule, median on subtending vein, subelliptic, ca. 4 mm; indusia yellowish brown, semi-elliptic, membranous, with thin hyaline margin with short 1-3-celled uniseriate hairs, rolling back at maturity, opening toward costule, persistent.
Streamsides, forests; 900-2600 m. Fujian, Guizhou, Hunan, Sichuan, Taiwan, Xizang, Yunnan [Bhutan, N India, N Myanmar, Nepal, N Vietnam].
Asplenium bullatum was confused with A. bulbiferum G. Forster by, e.g., Hooker (Sp. Fil. 3: 196. 1860) p.p., Beddome (Ferns Brit. India 1: 65. 1865; Handb. Ferns Brit. India, 159. 1883), Clarke (Trans. Linn. Soc. London, Bot. 1: 485. 1880), Christensen (Index Filic. 103. 1905) p.p., Panigrahi (Bull. Bot. Surv. India 2: 313. 1960), and Ching and Wu (Fl. Xizang. 1: 184. 1983).
Plants of Asplenium bullatum from Nepal are octoploid (Matsumoto & Nakaike in Watanabe & Malla, Cryptog. Himalayas 1: 179. 1988), unlike the tetraploids known from the E Himalaya (Bir, Curr. Sci. 29: 446. 1960). Further studies are needed to find out possible correlations with the dissection of the lamina, which varies from 2-pinnate to 4-pinnatifid, and with the more divided forms considered typical and recognized as A. bullatum var. bullatum (大盖铁角蕨(原变种) da gai tie jiao jue (yua bian zhong)). Bipinnate forms have been called A. bullatum var. shikokianum (Makino) Ching & S. H. Wu (FRPS 4(2): 75. 1999; 稀羽铁角蕨 xi yu tie jiao jue). However, A. ×shikokianum Makino (Bot. Mag. (Tokyo) 13: 13. 1899, pro sp., described from Japan) is the name for the natural hexaploid (Shimura & Matsumoto, J. Jap. Bot. 51: 235-244. 1976) hybrid between A. wrightii and A. ritoense and should not be used to describe the less-divided forms of A. bullatum (e.g., H. S. Kung, Fl. Sichuan. 6: 381. 1988; Wu, FRPS 4(2): 75. 1999; P. S. Wang & X. Y. Wang, Pterid. Fl. Guizhou, 139. 2001, p.p.; Li, Fl. Hunan 1: 288. 2004, p.p.). Many specimens currently filed in Chinese herbaria as A. shikokianum or as A. bullatum var. shikokianum have good spores and are not hybrids. True A. ×shikokianum is not uncommon where its parents grow together (e.g., Guizhou, Taiwan). Asplenium ×wangii C. M. Kuo (Bot. Bull. Acad. Sin. 29: 109-111. 1988), the hybrid between A. bullatum and A. wrightii, is morphologically similar to A. ×shikokianum and could be confused. Asplenium ×wangii was described from Taiwan and may be present where the parent taxa grow together (Fujian, Guizhou, Hunan, Sichuan, Taiwan, and Yunnan).