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 zollingeri Mett. ex Kuhn, Ann. Mus. Bot. Lugduno-Batavi 4: 280. 1869; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 109. 1967; Holttum, Rev. Fl. Malaya, ed. 2, 2: 638. 1968; Tagawa & K.Iwats., Fl. Thailand 3: 208, f. 16.3. 1985; Boonkerd & Pollawatn, Pterid. Thailand: 119. 2000; Newman et al., Checkl. Vasc. Pl. Lao PDR: 31. 2007.

Adiantum caudatum var. subglabrum Holttum, Rev. Fl. Malaya ed. 1, 2: 600. 1955 [‘1954’].

Description

Terrestrial or lithophytic. Rhizome short, erect, densely scaly at apex; scales linear, 4–6 mm long, 0.10.3 mm wide, margin entire, bicoloured with a darker centre and paler margin. Stipes 5–15 cm long, castaneous to nearly black, densely hairy with long, multicellular, brown hairs, scaly at base. Laminae linear, pinnate, gradually narrowing upwards, 12–44 by 1.5–4.5 cm; rachis hairy on upper surface, perfectly glabrous on lower surface, usually prolonged, sometimes leafless on upper part, often rooting at tip; 23–39 pairs of lateral pinnae, upper lateral pinnae becoming smaller and more spaced; lower pinnae smaller and reflexed; larger pinnae sessile, nearly parallelogram-shaped, round at apex, lower margin almost straight, to form narrowly cuneate base with lower margin, 7–22 by 3–11 mm, upper and outer margins lobed at most to less than 1/3 of width of pinnae, forming distinct sinus; lobes round or spathulate, round to subtruncate and slightly toothed at apex, each including 5 to 7 veinlets; papyraceous, almost glabrous or very sparsely hairy on veins and at margin of pinnae; veins rather indistinct on both surfaces. Sori on apices of lobes, reflexed flaps circular or elongate, glabrous or sparsely hairy .

Distribution in Thailand

NORTHERN: Mae Hong Son, Chiang Mai, Lamphun, Lampang, Phrae, Tak; NORTH-EASTERN: Phetchabun, Loei; EASTERN: Chaiyaphum, Nakhon Ratchasima; SOUTH-WESTERN: Uthai Thani, Kanchanaburi, Ratchaburi, Phetchaburi, Prachuap Khiri Khan; CENTRAL: Nakhon Nayok; PENINSULAR: Surat Thani, Phangnga, Nakhon Si Thammarat, Satun.

Distribution in Cambodia

Wider Distribution

Himalaya to W Malesia.

Ecology

On dry ground or on muddy limestone in deciduous or evergreen forests up to 1100 m altitude.

Similar species

Adiantum caudatum L.

Proposed IUCN Conservation Assessment

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

Notes

The hairiness is somewhat variable, especially on the pinnae. In some cases, pinnae are almost glabrous even in the young stages, though there are plants with hairy pinnae. The lobing of the pinnae is also fairly characteristic, not so deeply incised as in A. caudatum.

Voucher specimens - Thailand

Geesink et al. 6945, Chaiyaphum, Ban Lui Lai (P).

Voucher specimens - Cambodia

Long et al. CL334 & CL346, Mondulkiri (P).