Pteris ensiformis Burm.f.
Pteridaceae, subfamily Pteridoideae
Pteris ensiformis Burm.f., Fl. Indica.: 230. 1768; Bedd., Handb. Ferns Brit. India: 107. 1883; E.Smith, J. Siam Soc. Nat. Hist. Suppl. 8: 4. 1929; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 149. 1940; Holttum, Rev. Fl. Malaya ed. 1, 2: 399, f. 231. 1955 [‘1954’]; Holttum, Dansk Bot. Ark. 20: 27. 1961; Holttum, Dansk Bot. Ark 23: 235. 1965; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 79. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 234. 1985; Boonkerd & Pollawatn, Pterid. Thailand: 128. 2000.
Rhizome short creeping, bearing rather close fronds, about 5 mm diam., densely scaly; scales up to 4 by 0.7 mm, lanceolate with a long tail, brown, entire. Frond distinctly dimorphic. Sterile frond: stipe 7–15 cm long, brown and scaly at base, stramineous upwards, grooved on abaxial surface; lamina oblong, acute at apex, tripinnatifid, about 15 by 7 cm; pinnae 2–5 pairs, opposite, with a few pairs of pinnules and large apical segments; pinnules simple to trifoliolate, the ultimate segments oblong to oblong-lanceolate, apex moderately acute or acuminate in larger ones, 1.5–4(–7) by 0.7–1 cm, minutely serrate at margin; veins ascending, forked, all free, firm, green. Fertile frond taller; stipe 20–55 cm long; lamina bipinnate at base, up to 30 by 20 cm; pinnae a few pairs, simple to trifoliolate, ultimate segments linear, 7–17 by 0.5–1 cm, caudately acuminate at apex, broadly cuneate to subtruncate at base, serrate at upper non-soriferous margin. Sori linear, submarginal, continuous almost from base to apex; indusia pale green.
Distribution in Thailand
NORTHERN: Chiang Mai, Lampang, Tak; NORTH-EASTERN: Loei, Khon Kaen, Nakhon Phanom; EASTERN: Chaiyaphum; SOUTH-WESTERN: Uthai Thani, Kanchanaburi, Prachuap Khiri Khan; SOUTH-EASTERN: Chon Buri, Rayong, Chanthaburi, Trat; PENINSULAR: Chumphon, Surat Thani, Phangnga, Nakhon Si Thammarat, Krabi, Phatthalung, Trang, Satun, Pattani, Yala.
Distribution in Laos
Vientiane, Xieng Khouang.
Distribution in Cambodia
Tropics of Old World, Sri Lanka to Australia and Polynesia throughout Malesia, north to India, S China, Indochina and the Ryukyus.
On mountain slopes or on ground of tropical rain forests at low altitudes in Peninsular, or in dry evergreen forests at low to medium altitutdes in other parts.
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. 4710, Chanthaburi, Khao Soi Dao Wildlife Sanctuary (E).
Voucher specimens - Laos
Maxwell 99-121, Vientiane (CMU); Poilane 2324, Xieng Khouang (P).
Voucher specimens - Cambodia
Bouillod 74, Kampot, Kamchay (P); Harmand s.n., Pursat (P).
Old marginal sori
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