Family

Oleandraceae

Nomenclature

Oleandra undulata (Willd.) Ching, Lingnan Sci. J. 12: 565. 1933; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 286, f. 30.1 & 30.2. 1940; Holttum, Rev. Fl. Malaya ed. 1, 2: 384, f. 223. 1955 [‘1954’]; Holttum, Dansk Bot. Ark. 20: 26. 1961; Holttum, Dansk Bot. Ark. 23: 235. 1965; Ching, Fl. Reipubl. Popularis Sin. 2: 322, pl. 29, f. 1–4. 1959; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 78. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 180. 1985; Boonkerd & Pollawatn, Pterid. Thailand: 239. 2000. – Polypodium undulatum Willd., Sp. Pl. 5: 155. 1810.

Oleandra cumingii Hook. & Baker, Syn. Fil.: 303. 1867; Bedd., Handb. Ferns Brit. India: 288. 1883.

Oleandra pubescens Copel., Univ. Calif. Publ. Bot. 12: 397, pl. 52–a. 1931.

Description

Rhizome long creeping, 3–5 mm diam., bearing distant fronds, or rather closely on some portions, densely scaly throughout; scales appressed, oblong, round to moderately acute at basal edge, acuminate at apical edge, up to 7 by 1.3 mm, entire, brown, dark near attached points, long downy hairy. Fronds simple. Stipes on tall phyllopodia 1.5–12 cm high, stramineous, hairy, up to 20 cm or more long including phyllopodium. Laminae narrowly lanceolate, gradually narrowing towards both ends, up to 30 by 4.5 cm, the margin entire but more or less undulate, herbaceous to softly papyraceous; veins once or twice forked near midribs, densely hairy beneath, glabrous to densely hairy above, glabrous to densely hairy at margin of lamina. Sori in one regular row close to costa or rather irregularly arranged near costa, dorsal on acroscopic veinlets; indusia up to 2.2 mm broad, hirsute or glabrescent .

Distribution in Thailand

NORTHERN: Chiang Mai, Chiang Rai, Lampang, Phrae; NORTH-EASTERN: Loei; EASTERN: Chaiyaphum, Ubon Ratchathani; SOUTH-WESTERN: Kanchanaburi; SOUTH-EASTERN: Chanthaburi, Trat; PENINSULAR: Ranong, Phangnga, Krabi, Nakhon Si Thammarat.

Distribution in Laos

Champasak.

Distribution in Cambodia

Kompong Speu.

Wider Distribution

Burma and S China to Peninsular Malaysia.

Ecology

The habitats of this species are varied according to the localities: terrestrial on rather dry, slopes in mixed forests, growing in crevices of rocks in open areas or in light shade, or on limestone hills in evergreen forests, or epiphytic on tree trunks.

Proposed IUCN Conservation Assessment

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

Voucher specimens - Thailand

Middleton et al. 4932, Chiang Mai, Road to Ban Ung from Ban Mae Na Chon (E); Middleton et al. 5182, Ubon Ratchathani, Phu Chong Nayoi National Park (E).

Voucher specimens - Laos

Maxwell 97-1082, Champasak (CMU); Thorel 2467, Champasak, Kong (P).