Hymenasplenium apogamum (N.Murak. & Hatan.) Nakaike
Hymenasplenium apogamum (N.Murak. & Hatan.) Nakaike, New Fl. Jap. Pterid. 841. 1992. – Asplenium apogamum N.Murak. & Hatan., J. Fac. Sci. Univ. Tokyo, Sect. 3, Bot. 14: 193. 1988; Boonkerd & Pollawatn, Pterid. Thailand: 138. 2000.
Asplenium unilaterale auct. non Lam.: Tagawa & K.Iwats., Fl. Thailand 3: 277. 1985.
Rhizome long creeping, 3–4 mm diam., bearing many roots on ventral and two rows of fronds on dorsal surfaces, scaly; scales gradually narrowing from base towards hair-pointed apex, up to 4 by 0.5 mm, dark brown to nigrescent, clathrate. Stipes close or up to 1 cm apart, castaneous to purplish, polished, scaly near the base, 10–25 cm long. Frond pinnate, lanceolate, broadest at basal 1/5–1/8 portion, almost parallel or slightly narrowing upwards and then rather suddenly narrowing to caudate or acute apex, 10–20 (–35) cm long, about 4 cm (sometimes up to 9 cm) wide; rachis terete throughout; pinnae usually 20–30 pairs, roundly quadrangular, posterior half of lower portion dimidiate, truncate and slightly auricled at acroscopic base, rounded at apex, lobed to 1/5 way at upper and anterior half of lower margin, lobes rounded, oblique, moderately acute to rounded at apex, commonly 20 by 6 mm, sometimes up to 40 by 10 mm, a few lowest pairs shortly stalked, slightly smaller, more or less reflexed, thin, herbaceous, light green; veins visible. Sori 4–6 mm long; indusia herbaceous , pale, opening towards anterior side.
Distribution in Thailand
NORTHERN: Chiang Mai, Chiang Rai, Lampang, Tak; SOUTH-WESTERN: Kanchanaburi; CENTRAL: Nakhon Nayok; SOUTH-EASTERN: Chanthaburi, Trat; PENINSULAR: Chumphon, Ranong, Surat Thani, Nakhon Si Thammarat, Trang, Pattani, Yala.
Distribution in Laos
Widely distributed throughout the Old World tropics, north to central Japan.
Terrestrial on wet sandy slopes on moist muddy rocks along streams in dense primeval forests at 700–1800 m alt.
Proposed IUCN Conservation Assessment
Least Concern (LC). This species is widespread and not under any known threat.
Voucher specimens - Thailand
Middleton et al. 4889, Chiang Mai, Doi Inthanon National Park (E); Middleton et al. 4687, Chanthaburi, Khlong Khrue Wai Wildlife Sanctuary (E); Middleton et al. 4691, Chanthaburi, Khlong Khrue Wai Wildlife Sanctuary (E); Middleton et al. 4643, Trat, Khlong Kaew National Park (E); Middleton et al. 4354, Surat Thani, Khlong Phanom National Park (E); Middleton et al. 5541, Nakhon Si Thammarat, Namtok Si Khit National Park (E).
Voucher specimens - Laos
Poilane 2169, Xieng Khouang, Traninh (P).
Pinnae from above
Lower surface of lamina
Lower surface of lamina
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