Dryopteris subtriangularis (C.Hope) C.Chr.

Family

Dryopteridaceae

Nomenclature

Dryopteris subtriangularis (C.Hope) C.Chr., Index Filic.: 296. 1905; Ching, Bull. Fan Mem. Inst. Biol. 8: 96. 1938; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 315, f. 35.1 & 35.2. 1941; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 96. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 355. 1988; Boonkerd & Pollawatn, Pterid. Thailand: 205. 2000. – Nephrodium subtriangulare C.Hope, J. Bot. 28: 327. 1890. – Type: Mann s.n., Sept. 1888, India, Khasia (syntype P); Mann s.n., March 1890, India, Jaintea Hills (syntype P).

Dryopteris chapensis auct. non C.Chr. & Ching: Holttum, Dansk Bot. Ark. 20: 30. 1961, p.p.

Description

Rhizome short, erect, densely scaly at apex; scales linear, entire, 7–11 by 0.6–0.7 mm, nearly black. Stipes dark stramineous to pale brown, densely scaly at base, sparsely upwards, upper scales smaller, 13.5–36.5 cm long. Laminae oblong-ovate with acuminate apex, 18–35 by 12.5–24 cm, bipinnate to tripinnatifid at base; rachis like the upper part of stipe, with linear scales, grooved above; pinnae subopposite, 10–18 pairs of lateral pinnae of which 2–6 pairs are pinnate and the rest pinnatifid or simple, shortly stalked, narrowly subtriangular, caudate-acuminate at apex, subtruncate to broadly cuneate at base, 7–17.5 by 2.8–6 cm; pinna-rachis bullate-scaly, slightly ascending; pinnules oblong to oblong-subdeltoid, rounded to obtuse at apex, broadly cuneate and auricled on both sides at base, up to 2.5 by 1 cm, lobed almost to the base in larger ones, light green in living condition, drying brown; softly papyraceous, rather thin but coarse. Sori dorsal on veinlets, medial; indusia about 0.7 mm diam., fugacious .

Distribution in Thailand

NORTHERN: Chiang Mai; NORTH-EASTERN: Loei; CENTRAL: Nakhon Nayok.

Wider Distribution

NE India, S China and N Vietnam.

Ecology

On rather dry sandy slopes in mountain forests at 1000–1200 m alt.

Proposed IUCN Conservation Assessment

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

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