Polystichum attenuatum Tagawa & K.Iwats.
Polystichum attenuatum Tagawa & K.Iwats., Acta Phytotax. Geobot. 23: 113, f. 9. 1968; Tagawa & K.Iwats., Fl. Thailand 3: 335, f. 29.35. 1988; Boonkerd & Pollawatn, Pterid. Thailand: 208. 2000. – Polystichum sp.; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 94. 1967.
Rhizome short, scaly at apex; scales oblong with acuminate apex, rounded at base, up to 10 by 7 mm, rigid, bicoloured with nearly black central portion and light brown margin, marginal portion caducous, often leaving concolorous black scales on older portion of rhizome. Stipes 15–25 cm long. Laminae narrowly subtriangular, commonly widest at base, 30–45.5 by 15–25 cm; rachis scaly with brown linear scales less than 0.7 mm broad, with bulbil on rachis near apex; lateral pinnae 30 pairs or more, oblong or slightly narrowing from base to apex, falcate, auricled at acroscopic base, dimidiate at basiscopic base, upper ones pinnatifid, a few lowest pinnae very shortly stalked, patent, slightly falcate, lanceolate, up to 12.5 cm long, up to 2.5 cm wide; basal acroscopic pinnules about 1.5 times larger than the next; costae scaly, narrowly winged; pinnules of lower pinnae oblong or more usually narrowing from base to acute apex, auricled at acroscopic and dimidiate at basiscopic bases, apex of lobes ending in awns; veins minutely scaly beneath, not raised on both surfaces; subcoriaceous, glabrous on laminar surface, green. Sori terminal on vein, close to midrib of pinnule or medial; indusia small, glabrous, caducous .
Distribution in Thailand
NORTHERN: Chiang Mai; NORTH-EASTERN: Loei; SOUTH-WESTERN: Phetchaburi; SOUTH-EASTERN: Chanthaburi.
N India, S China, Thailand.
Terrestrial on humus-rich mountain slopes in dense evergreen forests at 1200–1800 m alt.
Proposed IUCN Conservation Assessment
Least Concern (LC). This species is widespread outside of Thailand and not under any known threat.
Voucher specimens - Thailand
Middleton et al. 4942, Chiang Mai, Doi Pha Ti Do (E); Middleton et al. 3300, Phetchaburi, Kaeng Krachan (A, BKF, E).
Base of stipe with scales
Upper surface of lamina
Rachis and bases of pinnae
Lower surface of pinnae
Lower surface of pinnules
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