Diplopterygium longissimum (Blume) Nakai
Diplopterygium longissimum (Blume) Nakai, Bull. Natl. Sci. Mus. 29: 53. 1950. – Gleichenia longissima Blume, Enum. Pl. Javae: 250. 1828; Holttum, Rev. Fl. Malaya ed. 1, 2: 67. 1955 [‘1954’]; Holttum, Fl. Males., Ser. II, Pterid. 1: 13, f. 4b–g. & 5. 1959; Tagawa & K.Iwats., Fl. Thailand 3: 52. 1979; Boonkerd & Pollawatn, Pterid. Thailand: 80. 2000.
Gleichenia norrisii auct. non Mett. ex Kuhn: Tagawa & K.Iwats., SouthE. Asian Stud. 5: 35. 1967, p.p.
Description from Holttum, Fl. Males., Ser. II, Pterid. 1: 14. 1959.Terrestrial. Rhizome dichotomously branched, near the apex protected by peltate scales. Fronds of mature plants usually with indefinite growth in length, bearing primary branches in pairs. Scales on resting apex of rachis nearly black, gradually narrowed towards apex, 1 mm or more in length, edges fringed with spreading pale hairs 0.5 mm long; young expanding parts of fronds covered with loose indumentum of narrow rust-coloured scales and lax stellate hairs, a few such scales and hairs sometimes persistent on lower surface of costae and costules, mature rachises quite smooth and glabrous. Primary rachis-branches to about 200 cm long and 40 cm wide; largest pinnules 15–22 cm long, 2.5–3.5 cm wide, costae 2.8–3.5 cm apart; lamina thin, lobed almost to costa, costules 4–5 mm apart, slightly oblique to costa; segments of lamina slightly narrowed above the base, edges slightly reflexed when dry; lower surface glaucous, veins slender and slightly raised; upper surface of rachis and costae glabrous, lamina slightly raised on each side of costae; veins on upper surface slightly raised near base, rarely also distally, very slender; sori usually of 3 sporangia , surrounded by crisped brown hairs.
Distribution in Thailand
NORTH-EASTERN: Phetchabun; PENINSULAR: Nakhon Si Thammarat, Krabi.
Throughout Malesia to Polynesia and Australia.
On rather dry slopes in clearings at medium altitude.
Proposed IUCN Conservation Assessment
Least Concern (LC). This species is widespread and not under any known threat.
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