Family

Pteridaceae, subfamily Pteridoideae

Nomenclature

Pteris heteromorpha Fée, Mém. Foug., 5. Gen. Filic.: 127. 1852; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 147. 1940; Holttum, Dansk Bot. Ark. 23: 235. 1965; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 82. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 241, f. 18.1. 1985; Boonkerd & Pollawatn, Pterid. Thailand: 128. 2000; Newman et al., Checkl. Vasc. Pl. Lao PDR: 31. 2007. – Pteris cretica var. heteromorpha (Fée) Bedd., Handb. Ferns Brit. India: 106. 1883.

Description

Rhizome short, erect, densely scaly at apex; scales linear, up to 5 mm long, concolorously brown, toothed at margin. Stipes stramineous or shining deep castaneous, 20–60 cm long. Laminae pinnate with irregularly lobed pinnae, usually broadly oblanceolate in outline but rather variable in form, 25–60 by 15–30 cm; rachis stramineous or deep castaneous, pubescent; lateral pinnae 3–8, of various different shapes, sometimes simple and linear with rounded and sessile base, margin entire, and up to 20 cm by 8–10 mm, other times deeply lobed and rounded at sessile base with caudately acuminate and with unlobed apical portion, and up to 25 by 7 cm, apical pinnae simple or irregularly lobed, up to 30 by 6 cm in lobed portion; ultimate segments irregular in size, form and position, usually long and regularly arranged on acroscopic side, sometimes dimidiate on basiscopic side and towards base and apex, usually more or less falcate, rounded to moderately acute, entire, 8–10 mm wide, length variable, softly leathery, green, pubescent on both sides; veins forked, more or less visible on both surfaces. Sori continuous along margin, of simple pinnae or segments, interrupted only at apex of segments and at sinus; indusia white, thin but firm , narrow, less than 0.5 mm wide.

Distribution in Thailand

NORTHERN: Mae Hong Son, Chiang Mai, Chiang Rai, Lampang, Phitsanulok; NORTH-EASTERN: Sakon Nakhon; SOUTH-WESTERN: Kanchanaburi; SOUTH-EASTERN: Chon Buri; PENINSULAR: Krabi.

Distribution in Laos

Champasak.

Distribution in Cambodia

Mondulkiri.

Wider Distribution

Burma, Vietnam, Luzon and Sulawesi.

Ecology

On rather dry humus slopes in dry or evergreen forests at 500–900 m alt.

Similar species

Pteris cretica L.

Proposed IUCN Conservation Assessment

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

Notes

The status of this species is uncertain as the fronds are highly heteromorphic. A specimen with three fronds from one plant has one frond simply pinnate with 6 pairs of simple entire pinnae similar in appearance to Pteris cretica ; the second has 7 pairs of pinnae each with 3–5 irregularly placed pinnules; and the third is a frond with 8 pairs of pinnatisect pinnae with more than 20 pairs of rather regularly placed lateral pinnules and long apical pinnules. The first and second leaves have stramineous stipes and the third castaneous ones.  Long et al. CL417 (P) from Cambodia has microscopically hairy margins to the indusia and those of Thai specimens are not.

Voucher specimens - Cambodia

Long et al. CL417, Mondulkiri (P).