Family

Polypodiaceae

Nomenclature

Microsorum membranaceum (D.Don) Ching, Bull. Fan Mem. Inst. Biol. 4: 309. 1933; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 478. 1941; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 52. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 526, f. 53.2. 1989; Nooteboom, Blumea 42: 338. 1997; Boonkerd & Pollawatn, Pterid. Thailand: 280. 2000. – Polypodium membranaceum D.Don, Prodr. Fl. Nepal.: 2. 1825; C.Chr., Contr. U.S. Natl. Herb. 26: 334. 1931. – Pleopeltis membranacea (D.Don) T.Moore, Index Fil.: 191. 1860; Bedd., Handb. Ferns Brit. India: 355. 1883.

Description

Rhizome creeping, up to 6 mm or more diam., bearing closely spaced fronds, usually near apical portion, scaly; scales larger, oblong-subtriangular, gradually narrowing towards apex, up to 10 by 2.5 mm, clathrate with smaller cells, bi-coloured, the central portion dark greyish-brown, the margin brown and more or less fringed. Stipes about 12 cm long, winged almost to the base, stramineous or greenish. Laminae narrowly oblong, broadest in lowermost 1/4 to 1/6, roundly narrowing and then attenuate to the base, gradually narrowing towards acuminate apex, subentire to slightly wavy at margin, up to 70 by 15 cm; midrib raised prominently beneath, main lateral veins prominent, main areoles visible, smaller areoles hardly visible, many in number and irregularly arranged; membranous to thinly herbaceous. Sori at joint of veins, round and distinct, small, irregularly scattered usually in 2–5 rows between main lateral veins, up to 1.5 mm diam.

Distribution in Thailand

NORTHERN: Mae Hong Son, Chiang Mai, Chiang Rai, Lamphun, Lampang, Tak.

Distribution in Laos

Xieng Khouang.

Wider Distribution

Sri Lanka, Himalayas to S China, Taiwan, N Vietnam.

Ecology

On mossy tree trunks in dense evergreen forests or on moist rocks by streams in dense forests, common at high altitudes in the North.

Proposed IUCN Conservation Assessment

Least Concern (LC). This species is common and widespread and not under any known threat.

Voucher specimens - Thailand

Middleton et al. 4462, Chiang Mai, Doi Suthep-Doi Pui National Park (E); Middleton et al. 4914, Chiang Mai, Doi Inthanon National Park (E).