Asplenium prolongatum Hook.
Asplenium prolongatum Hook., Sec. Cent. Ferns: Pl. 42. 1860; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 242. 1940.
Plants 20-40 cm tall. Rhizomes short and erect, apexes densely covered with scales; the scales lanceolate, black, polished and with brown narrow edges, entire or denticulate along margins. Fronds clustred; stipes 8-18 cm long, greenish, longitudinal-valleculate on upper sides, after dry compressed and laminae all sparsely covered with darkkish-brown fibrous small scales when young, then fallen and smooth; laminae linear-lanceolate, 10-25 x 3-4.5 cm, apexes caudate, bipinnate; pinnae 20-24 pairs, lower (or basel ) ones opposite, up ones alternate, subsessile, lower pinnae usually unshortened, midd ones 1.3-2.2 x 0.8-1.2 cm, narrowly elliptic, apexes rounded, bases asymmetrical, acroscopic truncate, bsiscopic obliquely cutting, pinnate; pinnules alternate, anadromous, 2-5 pieces on acroscopic, 0-3 (-4) pieces on basicopic, narrow-linear, 4-10 x 1-1.5 mm, apexes obtuse, bases combined with rachillae and connected by broad-wing, entire, acroscopic basel1-2 pieces 2-3 redivided, basel basiscopic one piece occasionally bidivided; segments same shape with pinnules but shorter. Veins obvious and bitly raised, one veinlet on pinnule or segment and with a hydathode at end, unreached to margins. Fronds subcarnse, after dry grass-green; rachises same colour with stipe, apexes ususally prolongating into flagellating and rooting, rachillae same colour with lamina, raised on upper sides, both lateral sides winged. Sori linear, 2.5-5 mm long, deeply brown, one on per pinnule or segment, located on acroscopic margins on middle of pinnules; indusia linear, greyish-gren, membranous and entire, openning to margins and persistent .
Distribution in Laos
Japan, China, India, Sri Lanka, Laos, Vietnam.
Proposed IUCN Conservation Assessment
Least Concern (LC). This species is widespread and not under any known threats.
Voucher specimens - Laos
Delacour s.n., Khammouane, Nape (P).
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