Polystichum eximium (Kuhn) C.Chr.

Family

Dryopteridaceae

Nomenclature

Polystichum eximium (Mett. ex Kuhn) C.Chr., Index Filic. Suppl. III: 163. 1934; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 94. 1967, p.p.; Tagawa & K.Iwats., Fl. Thailand 3: 336. 1988; Boonkerd & Pollawatn, Pterid. Thailand: 208. 2000. – Phegopteris eximia Mett. ex Kuhn, Linnaea 36: 107 1869.

Polystichum setiferum auct. non (Forssk.) T.Moore ex Woynar: C.Chr., Contr. U.S. Natl. Herb. 26: 330. 1931.

Description

Rhizome short, ascending; scales oblong-subdeltoid, acuminate to tailed at apex, up to 20 by 4 mm, entire, bicoloured, central portion shining black, rigid and tough, margin brown, thinner. Stipes stramineous, 25–60 cm long, scaly throughout; scales at base very dense, consisting of two kinds, one like those on rhizome, the other linear, concolorous, brown, serrate at margin, scales on upper part of stipe linear, up to 1 cm long, at most 0.5 mm broad, black or dark brown. Laminae oblong-lanceolate, widest at middle, 35–50 by about 25 cm; rachis gemmiferous, scaly throughout; pinnae more than 15 pairs, patent or slightly ascending, lower ones lanceolate, broadly cuneate at base, acuminate at apex, more or less falcate, 10–13 by 3–3.5 cm, shortly stalked; pinna-rachis scaly underneath, grooved on upper surface; pinnules close to imbricate, oblong or narrowing from base to apex, falcate, acute at apex, slightly auricled at acroscopic and dimidiate at basiscopic bases, 15–25 by 7–10 mm; veins a little raised on lower surface; coriaceous, green, glabrous on laminar surface. Sori submarginal or scattered on lower surface of pinnules; indusia about 1.2 mm diam., persistent .

Distribution in Thailand

NORTHERN: Chiang Mai, Chiang Rai; NORTH-EASTERN: Loei.

Wider Distribution

According to the current definition of this species found in tropical Asia from Sri Lanka northwards to southern edge of Japan.

Ecology

On mountain slopes in dense evergreen forests at 700–1200 m alt.

Proposed IUCN Conservation Assessment

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

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