Phymatosorus longissimus (Blume) Pic.Serm.
Phymatosorus longissimus (Blume) Pic.Serm., Webbia 28: 459. 1973; Boonkerd & Pollawatn, Pterid. Thailand: 282. 2000. – Polypodium longissimum Blume, Enum. Pl. Javae: 127. 1828. – Phymatodes longissima (Blume) J.Sm., Cult. Ferns: 10. 1857; Ching, Contr. Inst. Bot. Natl. Acad. Peiping 2: 62. 1933; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 476. 1941; Holttum, Rev. Fl. Malaya ed. 1, 2: 191. 1955 [‘1954’]. – Pleopeltis longissima (Blume) T.Moore, Index Fil.: lxviii. 1857; Bedd., Handb. Ferns Brit. India: 366. 1883. – Type: Blume 35, Java. (L).
Microsorum rubidum (Kunze) Copel., Gen. Fil.: 197. 1947; Tagawa & K.Iwats., SouthE Asian Stud. 5: 53. 1967; Tagawa & K.Iwats., Acta Phytotax. Geobot. 23: 53. 1968; Tagawa & K.Iwats., Fl. Thailand 3: 532, f. 53.5. 1989; Nooteboom, Blumea 42: 356. 1997; Bosman et al., Fl. Males., Ser. II, Ferns and Fern Allies 3: 125. 1998. – Polypodium rubidum Kunze, Bot. Zeit. 1848: 117. 1848. – Type: Cuming 241, Luzon, Philippines. (BM, E, K, L, P, US).
Rhizome creeping, thick, 5–8 mm diam., bearing stipes remotely, dark on surface, scaly; scales oblong-subdeltoid, gradually narrowing towards apex, round at base, about 5 by 2.5 mm, irregularly toothed at margin, concolorously brown, more or less clathrate. Stipes thick, up to 1 cm diam. near base, up to 70 cm long, winged only on the upper portion. Laminae oblong, moderately acute at apex, up to 130 by 50 cm, pinnatisect with broadly winged rachis; lateral lobes about 25 pairs, linear-lanceolate, caudately acuminate at apex, entire at margin, a little narrowing at base and decurrent to rachis, 30 by 3 cm at lower or middle ones, more or less ascending; costa distinctly raised, lateral main veins distinct, the other veins visible, copiously anastomosing; herbaceous to thinly papyraceous, dark green, brownish in dried condition. Sori in one row arranged medially at each side of costa, round, about 2 mm diam., distinctly immersed in hollows which are prominently raised on upper surface.
Distribution in Thailand
NORTHERN: Lampang; PENINSULAR: Nakhon Si Thammarat, Yala.
India, Sri Lanka, throughout Malesia and Polynesia, north to Vietnam.
On rather wet rocks along rivers in light shade at low altitudes.
Proposed IUCN Conservation Assessment
Least Concern (LC). This species is widespread and not under any known threat.
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