Family

Polypodiaceae

Nomenclature

Pyrrosia angustissima (Giesenh. ex Diels) Tagawa & K Iwats, Acta Phytotax. Geobot. 26: 171. 1975; Ravensb. & Hennipman, Leiden Bot. Ser. 9: 297, f. 1 d,m,t, 2.b,k. 1986; Tagawa & K.Iwats., Fl. Thailand 3: 493, f. 50.1–2. 1989; Boonkerd & Pollawatn, Pterid. Thailand: 285. 2000. – Niphobolus angustissimus Giesenh. ex Diels in Engl. & Prantl, Nat. Pflanzenfam. 1(4): 326. 1899, based on Polypodium angustissimum Baker, Ann. Bot. 5: 472. 1891, non Fée 1869. – Saxiglossum angustissimum (Giesenh. ex Diels) Ching, Acta Phytotax. Sin. 10: 301. 1965.

Description

Rhizome long creeping, up to 1 mm or more diam., densely scaly throughout; scales narrowly oblong-subdeltoid with long-tailed apex and round base, entire, up to 5 mm long including the tails which are more than half the length, up to 0.7 mm broad, pale brown to brown with dark central portion. Fronds simple. Stipes indistinct or up to 2 cm long, densely scaly at base, stellate hairy or glabrescent. Laminae monomorphous, linear, round to moderately acute at apex, gradually narrowing towards base, involute, up to 12 cm by 4 mm, thick-leathery, sparsely stellate-hairy above, densely covered with short-armed stellate hairs as well as wooly hairs beneath, the margin usually broad and involuting to form a broad flap on the ventral side covering the sori in their early stage of development; veins hardly visible, forming loose anastomosis without free included veinlets. Sori elongate, at midway between midrib and margin of laminae, usually covered by the involute margin of laminae .

Distribution in Thailand

SOUTH-WESTERN: Kanchanaburi.

Wider Distribution

Warm part of China and Taiwan.

Ecology

Epiphytic, very high on dead trees in deciduous or evergreen forests, 700–1150 m alt.

Proposed IUCN Conservation Assessment

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