Cyclosorus siamensis (Tagawa & K.Iwats.) Panigrahi




Cyclosorus siamensis (Tagawa & K.Iwats.) Panigrahi, Res. J. Pl. Environ. 9: 67. 1993. – Thelypteris siamensis Tagawa & K.Iwats., Acta Phytotax. Geobot. 22: 101, f. 5. 1967; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 65. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 426, f. 44.7–9. 1988. – Christella siamensis (Tagawa & K.Iwats.) Holttum, Kew Bull. 31: 332. 1976; Boonkerd & Pollawatn, Pterid. Thailand: 221. 2000. – Type: Tagawa et al. 1277, Thailand, N. ridge of Phu Luang, 1400 m (KYO).


Rhizome erect; scales linear-lanceolate with long tails, c. 10 by 1.2 mm, sparsely hairy at margin. Stipes densely scaly at base, hirsute throughout, up to 50 cm long. Laminae oblong-lanceolate, acute at apex, up to 40 by 20 cm; a few lower pinnae slightly reduced, deflexed, auricled at acroscopic base, middle larger ones falcate, sessile, linear-lanceolate, long-acuminate at apex, broadly cuneate to truncate at base, up to 11 by 1.8 cm, lobed to 2/3 way to costa; segments oblong, oblique, rounded to moderately acute at apex, entire; papyraceous, hairy on surface; basal veinlets uniting to form goniopteroid venation. Sori medial to supramedial; indusia round-reniform, persistent, densely hirsute .

Distribution in Thailand

NORTHERN: Tak; NORTH-EASTERN: Phetchabun, Loei; PENINSULAR: Surat Thani.

Wider Distribution

Endemic to Thailand.


In evergreen forests at low to 1400 m alt.

Proposed IUCN Conservation Assessment

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


Only doubtfully distinct from Cyclosorus hispidulus (Decne.) Ching.

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