Asplenium prolongatum Hook.

Family

Aspleniaceae

Nomenclature

Asplenium prolongatum Hook., Sec. Cent. Ferns: Pl. 42. 1860; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 242. 1940.

Description

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

Khammouane.

Wider Distribution

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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