Pteris decrescens Christ

Family

Pteridaceae, subfamily Pteridoideae

Nomenclature

Pteris decrescens Christ, Bull. Acad. Int. Geogr. Bot. 16: 244. 1906; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 152. 1940; Holttum, Dansk Bot. Ark. 20: 27. 1961; Tagawa & K.Iwats., SouthE. Asian Stud. 3(3): 83. 1965; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 81. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 249, f. 20.2. 1985; Boonkerd & Pollawatn, Pterid. Thailand: 128. 2000.

Pteris hossei Hieron., Hedwigia 55: 372. 1914.

Pteris asperula auct. non J.Sm. ex Hieron.: Christ, Bot. Tidsskr. 20: 107. 1901.

Pteris quadriaurita var. blumeana auct. non Brouse: Hosseus, Beih. Bot. Centralbl. 28 (2): 366. 1910.

Pteris aspericaulis auct. non Wall. ex J.Agardh: C.Chr., Bot. Tidsskr. 32: 348. 1916.

Description

Rhizome short, erect, bearing a few fronds in a tuft, densely scaly at apex; scales linear, about 5 by 0.2 mm, deep purplish-brown, shining, with thin, pale brown ferrugineous margin. Stipes deep castaneous or purplish, shining, puberulous upwards, 20–58 cm long. Laminae oblong-lanceolate, deeply bipinnatisect, 20–47 by 20–30 cm; rachis castaneous, more or less shining, grooved on upper surface, hirsute beneath; lateral pinnae less than 10 pairs, subopposite, oblong with apex long caudate (with apical segments up to 5 cm long), broadly cuneate at sessile base, 10–20 by 2.5–4.5 cm, shortly stalked; costa grooved and with spines on upper surface, hirsute beneath; pinnules narrow, round or moderately acute at apex, slightly ascending, close to each other, 3–4.5 mm broad, papyraceous; veins forked, ascending, visible on both surfaces. Sori continuous along margin of pinnules from base to midway or almost to apex; indusia pale brown, firm .

Distribution in Thailand

NORTHERN: Chiang Mai, Chiang Rai, Lamphun, Phitsanulok; NORTH-EASTERN: Loei; EASTERN: Chaiyaphum; SOUTH-EASTERN: Chon Buri, Chanthaburi, Trat; PENINSULAR: Surat Thani.

Distribution in Laos

Champassak.

Distribution in Cambodia

Pursat.

Wider Distribution

S China and Indochina.

Ecology

On mountain slopes in deep shade at medium or high altitudes.

Proposed IUCN Conservation Assessment

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

Voucher specimens - Thailand

Middleton et al. 4717, Chanthaburi, Khao Soi Dao Wildlife Sanctuary (E); Middleton et al. 4881, Chiang Mai, Doi Inthanon National Park (E).

Voucher specimens - Laos

Thorel 2514, Champasak (P)

Voucher specimens - Cambodia

Harmand 435, Pursat (P).

Habit

Habit

Habit

Habit

Young plant

Young plant

Rhizome

Rhizome

Elongated apex to pinnae

Elongated apex to pinnae

Basal pinnae

Basal pinnae

Upper surface of lamina

Upper surface of lamina

Spines on costae above

Spines on costae above

Venation

Venation

Lower surface of lamina

Lower surface of lamina

Sori

Sori

Site hosted by the Royal Botanic Garden Edinburgh. Content managed by Stuart Lindsay, Gardens by the Bay, Singapore and David Middleton, Singapore Botanic Gardens. Last updated 16 November 2016.