Family

Polypodiaceae

Nomenclature

Drynaria rigidula (Sw.) Bedd., Ferns Brit. India: t. 314. 1869; Handb. Ferns Brit. India: 344, f. 192. 1883; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 521. 1941; Holttum, Rev. Fl. Malaya ed. 1, 2: 183, f. 90. 1955 [‘1954’]; Holttum, Dansk Bot. Ark. 20: 20. 1961; Holttum, Dansk Bot. Ark 23: 231. 1965; Tagawa, J. Jap. Bot. 38: 330. 1963; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 59. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 550. 1989; Hovenkamp & Roos, Fl. Males., Ser. II, Ferns and Fern Allies 3: 42. 1998; Boonkerd & Pollawatn, Pterid. Thailand: 250, 270. 2000; Newman et al., Checkl. Vasc. Pl. Lao PDR: 30. 2007. – Polypodium rigidulum Sw., Schrad. J. Bot. 1800(2): 26. 1801. – Type: Thunberg (S), Java.

Description

Rhizome short creeping, 6–20(–30) mm diam., densely scaly throughout; scales gradually narrowing from peltate rounded base to apex, pale brown with dark basal point, 5–10(–13) by 0.5–1.2(–1.5) mm, sparsely hairy at margin with pale long downy hairs. Nest-leaves sessile, narrowly oblong-subdeltoid, round at base, acute at apex, 10–35 by 5–10(–15) cm, lobed 1/3–4/5 way towards midribs; lobes subtriangular, round at apex, entire, up to 3 by 2 cm. Foliage-leaves: stipes pale castaneous to purple, more or less densely downy hairy, up to 20(–40) cm long, but usually very short, often bearing undeveloped pinnae at both sides of stipes; laminae pinnate, oblong-lanceolate, 25–100(–200) by 12–30(–50) cm; rachis pale purple, downy-hairy; lateral pinnae about 40 pairs, linear-lanceolate, 8–15(–25) by 0.5–1.4(–3) cm, sessile, subentire or serrate at margin, caudately acuminate at apex, unequally cuneate at base; costa pale stramineous, jointed to rachis; veins raised on both surfaces, anastomosing, 2 to 5 areoles between main veins. Sori round, close to costa, one row along each side of costa , one between main veins, raised on upper surface.

Distribution in Thailand

NORTHERN: Chiang Mai, Chiang Rai, Tak, Phitsanulok; NORTH-EASTERN: Loei; SOUTH-WESTERN: Kanchanaburi; CENTRAL: Nakhon Nayok; SOUTH-EASTERN: Chanthaburi; PENINSULAR: Surat Thani, Krabi, Yala.

Distribution in Laos

Luang Phrabang, Xieng Khouang.

Distribution in Cambodia

Kampot, Kompong Speu, Kompong Thom, Mondulkiri, Pursat.

Wider Distribution

Indochina, Burma, Malesia, Polynesia and tropical Australia.

Ecology

On tree tunks or in muddy crevices of cliffs in some open places or in deciduous or mixed forests at medium altitudes, rather common throughout the country.

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. 5060, Phitsanulok, Phu Hin Rong Kla National Park (E).

Voucher specimens - Cambodia

Middleton & Monyrak 608, Kampot, Bokor National Park (A, P); Bouillod 26, Kampot, Mt Kamchay (P); Martin 772, Kompong Speu, Kirirom (P);  Long et al. CL421, Mondulkiri (P); Pierre 5723, Kompong Thom, Sral Mts (P); Godefroy-Lebeuf 531, Pursat (P).