Etymology

According to Holttum (1954), the botanical name, Adiantum (unwetted) refers to the way in which water-drops run off the surface of the pinnae without wetting them.

Family

Pteridaceae, subfamily Vittarioideae

Nomenclature

Adiantum stenochlamys Baker, Ann. Bot. 5: 209. 1891; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 187. 1940; Holttum, Rev. Fl. Malaya ed. 1, 2: 602, f. 353. 1955 [‘1954’]; Ching, Acta Phytotax. Sin. 6: 328. 1957; Tagawa & K.Iwats., Acta Phytotax. Geobot. 23: 50. 1968; Tagawa & K.Iwats., Fl. Thailand 3: 215, f. 16.5. 1985; Boonkerd & Pollawatn, Pterid. Thailand: 119. 2000; Newman et al., Checkl. Vasc. Pl. Lao PDR: 31. 2007.

Adiantum fragiliforme C.Chr., Bot. Tidsskr. 32: 347. 1916.

Adiantum suborbiculare Alderw., Bull. Dept. Agric. Ind. Neerl. 18: 11. 1908; E.Smith, J. Siam Soc. Nat. Hist. Suppl. 8: 3. 1929.

Description

Terrestrial or lithophytic. Rhizome short erect, bearing a dense tuft of fronds, covered with scales; scales linear, slightly broader at base, entire, 7–8 mm long, golden brown, concolorous. Stipes terete, not grroved above, 2–30 cm long, dark reddish brown to blackish, shiny, glabrous except for scales at base.  Lamina perfectly glabrous, tripinnate at base, 5.5–21 by 4.5–24 cm; rachis terete, glabrous, black; c.3 pairs of pinnate pinnae, basal pinnae 2.5–15 cm long; leaflets fan-shaped, 6–15 by 6–17 mm, base obtuse to acute, distal margin round, sometimes lobed, thin, glabrous, glaucous beneath or not, distinctly stalked; veins not raised. Sori marginal, square to elongate, 1–8 to each pinnule .

Distribution in Thailand

SOUTH-EASTERN: Trat; PENINSULAR: Surat Thani, Satun, Songkhla.

Distribution in Laos

Unspecified.

Distribution in Cambodia

Kampot, Kompong Speu, Pursat

Wider Distribution

Cambodia, Vietnam, Peninsular Malaysia, Borneo and Philippines.

Ecology

On wet rocks in forests usually at low altitudes near sea.

Proposed IUCN Conservation Assessment

Least Concern (LC). This species is common and widespread.

Notes

A very variable species .  Following the Flora of Thailand Adiantum fragiliforme is included in synonymy here but further taxonomic work is necessary to see if this decision is correct .

Voucher specimens - Thailand

Middleton et al. 4624 & 4626, Trat, Ko Chang, Trail from Khlong Phlu Ranger Station (E).

Voucher specimens - Cambodia

Schnell 10068, Kampot, Elephant Mts (P); Pierre 5747, Kompong Speu, Mt Aral (P); Mueller  526, Pursat (P).