Family

Pteridaceae, subfamily Pteridoideae

Nomenclature

Pteris grevilleana Wall. ex J.Agardh, Recens. Spec. Pter.: 23. 1839; Bedd., Handb. Ferns Brit. India: 112. 1883; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 153. 1940; Holttum, Rev. Fl. Malaya ed. 1, 2: 402, f. 235. 1955 [‘1954’]; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 80. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 247. 1985; Boonkerd & Pollawatn, Pterid. Thailand: 128. 2000. – Pteris ensiformis var. grevilleana (Wall. ex J.Agardh) Bedd., Handb. Ferns Brit. India: 108. 1883; Bedd., Suppl. Ferns Brit. Ind.: 23.1892.

Description

Rhizome short, erect, scaly at apex; scales small, up to 3 by 0.5 mm, dark brown, entire. Frond dimorphic. Sterile frond: stipe shining, deep purple to pale castaneous, glabrescent upwards, 8–13 cm long, narrowly winged in upper portion; lamina ovate in outline, up to 15 by 10 cm, each consisting of a terminal pinna and one or rarely two pairs of lateral pinnae each bearing a large basiscopic pinnule almost as big as the pinna, thus seemingly pentaphyllous, terminal pinna deeply lobed to 3/4-way towards midrib, acute at apex, cuneate and decurrent at base continuing to wings of stipes, up to 10 by 3.5 cm, lateral pinnae narrower, up to 7 by 2.5 cm, rounded to cuneate, the basiscopic projections up to 4 by 1.5 cm; pinnules or ultimate lobes oblong, rounded at apex, serrate at margin, up to 6 mm wide, softly papyraceous, deep green; veins forked, hardly visible. Fertile frond taller: stipe 25–30 cm long; lamina like sterile one or with an additional lateral pair of pinnae smaller in size than the lowest one, larger, up to 10 by 14 cm. Sori continuous along margin of lobes except at apex and at sinus; indusia pale brown, thin.

Distribution in Thailand

NORTHERN: Phitsanulok; NORTH-EASTERN: Loei; CENTRAL: Nakhon Nayok; PENINSULAR: Surat Thani, Nakhon Si Thammarat.

Wider Distribution

India to S China and W Malesia, north to Taiwan and the Ryukyus.

Ecology

On humus-rich mountain slopes in dense evergreen forests at medium altitudes.

Proposed IUCN Conservation Assessment

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

Voucher specimens - Thailand

Middleton et al. 5529, Nakhon Si Thammarat, Khao Luang National Park (E).