Lygodium giganteum Tagawa & K.Iwats.

Family

Lygodiaceae

Nomenclature

Lygodium giganteum Tagawa & K.Iwats., Acta Phytotax. Geobot. 22: 97, f. 1. 1967; SouthE. Asian Stud. 5: 35. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 63, f. 4.10–4.13. 1979; Boonkerd & Pollawatn, Pterid. Thailand: 82. 2000.

Lygodium flexuosum auct. non (L.) Sw.: Holttum, Dansk Bot. Ark. 20: 15. 1961, p.p.; Tagawa & K.Iwats., SouthE. Asian Stud. 3(3): 72. 1965.

Description

Rhizome very short creeping, bearing fronds close together, the apex and bases of stipes densely covered with dark brown hairs. Fronds very large, climbing to more than 2 m; stipes at most 20 cm long, stramineous to dark, densely pubescent throughout, very narrowly winged; rachis like upper part of stipes, 2–4 mm diam., densely pubescent; primary rachis-branches 3–15 mm long, the apex dormant, densely covered with brown hairs; secondary rachis-branches pinnate to bipinnate, up to 25 cm long and wide; in larger ones tertiary rachis-branches with a few leaflets, forming a pentagonal outline, tertiary leaflets palmately 5-lobed to hastate, with large central lobes, deeply cordate at base, round or very moderately acute at apex; axes of branches of secondary and of higher order stramineous, densely pubescent with pale unicellular hairs, with distinct articulation at every junction; ultimate lobes larger, oblong-subdeltoid to oblong; round at apex, irregularly and slightly dentate at margin, herbaceous to softly papyraceous, up to 20 cm long, 4 cm broad, the stalks very narrowly, winged, articulate at base of lamina, up to 15 mm long; veins forked three to four times, all free; both surfaces of lamina as well as veins hairy. Sporangia-bearing lobes protruding at margin of the ultimate lobes, 2–8 mm long, about 1.2 mm broad; indusia hairy .

Distribution in Thailand

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

Wider Distribution

Upper Burma and Yunnan.

Ecology

On dry slopes in thickets, usually in deciduous forest at low or medium altitudes.

Proposed IUCN Conservation Assessment

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

Notes

In hairiness and articulation at base of ultimate segments (without actual function as abscission zone) this is similar to Lygodium salicifolium and rather difficult to distinguish from the latter in the Burma-Yunnan region. The pattern of division of the fronds is like that of Lygodium flexuosum but it is a much larger species ; smaller forms differ from Lygodium flexuosum in more dense hairs, distinct articulation, and thicker texture of lamina .

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